Keithley 775A User manual

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Instruction Manual
Model 775A
Programmable Counter / Timer
©1987, Keithley Instruments, Inc.
All rights reserved.
Any unauthorized reproduction, photocopy, or use the information herein, in whole or in part, without the prior written approval
of Keithley Instruments, Inc. is strictly prohibited.
All Keithley Instruments product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand names are trademarks or registered trademarks of their respective holders.
Cleveland, Ohio, U.S.A.
Document Number: 775-901-01 Rev. B / February 1987
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WARRANTY
Keithley instruments, Inc. warrants this product to be free from defects
in material and workmenship for a period of 1 year from date of ship-
ment. During the warranty period, we will, at our option, either repair
or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley represent-
ative, or contact Keithley headquarters in Cleveland, Ohio. You will be
given prompt assistance and return instructions. Send the instrument,
transportation prepaid, to the indicated service:facility. Repairs will be
made and the instrument returned, transportation prepaid. Repaired
products are warranted for the balance of the original warranty period,
or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from unauthorized
modification or misuse of any product or part. This warranty also does
not apply to fuses, batteries, or damage from battery leakage.
This warranty is in lieu of all other warranties, expressed or implied, in-
cluding any implied warranty of merchantability or fitness for a par-
ticular use. Keithley Instruments, Inc. shall not be liable for any indirect,
special or consequential damages.
STATEMENT OF CALIBRATION
This instrument has been inspected and tested in accordance with
specifications published by Keithley Instruments, Inc.
The accuracy and calibration of this instrument are traceable to the
National Bureau of Standards through equipment which is calibrated at
planned intervals by comparison to certified standards maintained in
the Laboratories of Keithley Instruments, Inc.
KEITHLEYINSTRUMENTS,INC.
INSTRUMENTDIVISIONI 29775 Aurora Road / Cleveland. Ohio 44139 / U.S.A. / 1216) 246-0400 / Telex: 99.5469
WESTQERMANY: Keithley Instruments GmbH / Heiglhofstr. 5 / 6000 Munchen 70 / 10691 710020 / Telex: 52.12160
aREA BRITAIN:Keithlay Instruments, Ltd. / 1, Boulton Road / Reading, Berkshire RG 2 ONL / 10734) 66-l 2.67/66 / Telex: 94.7047
FRANCE Keithlsy Instruments SARL / 2, Bis Rue L&n Blum / 9.P. 60 / 91121 P$laiseau Cedex / 16101 l-51 -55 /Telex: 600-933
NETHERLAND% Kelthley Instruments BV / Arkelsedijk 4 / Postbus 559 / 4200 AN Gorinchem / 1011930.25577 / Telex: 24-664
SWITZERLAND: Kelthley Instruments SA / Kriesbachstr. 4 / 9600 Oibendorf / 01/821-94-44 / Telex: 57-536
AUSTRI*: Keith@ lnatruments Ges.m.b.H. / Doblinger Haupstr. 32 / 1190 Wien / 314 299 / Telex: 13-4500
ITALY: Kelthley Instruments, SRL / Viale S. Gimignano 4/A / 20100 Milano, Italy / 4120360
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SPECIFICATIONS
INPUT CHARACTERISTICS PERIOD A
Channel A, B; each channel
RANGE: 0 to l20MHz, dc coupled.
30Hz to IZOMHz, ac coupled.
SENSITIVITY (d): 25mV rms, <lOMHz.
50mV rms, > 1OMHz.
RANGE: Mns to 10” seconds.
LSD DISPLAYED: 1Ons to O.lms.
ACCURACY:
*l LSD *(Time Base Error x Period) f Trigger Error.
PERIOD AVERAGE A
DYNAMIC RANGE (xl): 50mV to 5V pk-pk, <ZOMHz.
14OmV to 2.5V pk-pk, >20MHz.
COUPLING: ac or dc, switchable.
IMPEDANCE: lMR nominal, shunted by <60pF.
ATTENUATOR: xl or xl0 nominal, switchable.
LOW PASS FILTER: -1OdB at 1OOkHz nominal, switchable.
SIGNAL OPERATING RANGE (xl): -2.55V dc to t2.55V dc.
TRIGGER LEVEL: -2.55V dc to +2.55V dc, xl.
:25.5V dc to +25.5V dc, x10.
TRIGGER LEVEL RESOLUTION: lGmV, xl.
Mo”v, xx?
RANGE: 1Onsto 10sec.
LSD DISPLAYED: (10ns x l’eriod)/Gate Time.
RESOLUTION:
fl LSD f (1.4 x Trigger Error + Zns) x Period
Gate Time
ACCURACY: f Resolution *(Time Base Error x Period)
NUMBER OF PERIODS AVERAGED: Gate Time/Period
TIME INTERVAL A-B
RANGE: 1011sto lo4 seconds.
LSD DISPLAYED: 1Ons to O.lms.
ACCURACY: fl LSD *(Time Base Error x Time Interval)
f Trigger Error * Trigger Timing Error -t2ns.
TRIGGER LEVEL SElTING ACCURACY:
*(35mV + 2% of setting), xl.
*(35OmV + 2% of setting), x10
TRIGGER LEVEL SETTING OUTPUT: via rear panel BNC,
not adjusted for attenuators.
SLOPE: + or - slope, switchable.
DAMAGE LEVEL:
xl: dc-2kHz 250V dc + peak ac
2kHz-100kHz 5 x 1OsV rms*Hz/frequency
> 1OOkHz 5v rms
x10: dcZOkHz 250V dc + peak ac
20kHz.100kHz 5 x 10%’ rms.Hz/frequency
> 1OOkHz 5oVrms
Channel C (with Model 7751 option)
RANGE: 5OMHz to 1.3GHz.
SENSITIVITY: l5mV, 50MHz to l.OCHz;
25mV, l.OGHz to 1.2GHz;
75mV, 1.2GHz to 1.3GHz
DYNAMIC RANGE: 25mV rms to 1V rms.
COUPLING: ac.
IMPEDANCE: 500.
DAMAGE LEVEL:
dc-100kHz
>.lOOkHz l5V dc + peak ac 5v rms
FREQUENCY A, B
RANGE: O.lHz to l20MHz.
LSD DISPLAYED: (101~sx Frequency)/Cate Time
RESOLUTION:
*l ,.SD -t (1.4 x Trigger Error + 2ns)x Frequency
Gate Time
ACCL RACY:
*Resolution *(Time Base Error x Frequency)
DIGITS DISPLAYED: 8 per second of Gate Time, minimum.
PULSE WIDTH A (Positive or Negative)
RANGE: Mns to lo4 seconds.
LSD DISPLAYED: lOns to O.lms.
ACCURACY: fl LSD *(Time Base Error x Pulse Width)
f Trigger Error f Trigger Timing Error f2ns.
mALIZE A
MODES: Cumulative or A gated by B
RANGE: 0 to lo”-1
REPETITION RATE: lZ0MHz “ax.
LSD DISPLAYED: 1 count up to lOLo-1, then 9 most signifi-
cant digits.
ACCURACY: kl LSD
GATE/DELAY
INTERNAL GATE TIME: Variable from loops to IOsec in 45
increments, or one period of the input, whichever is longer.
May be used in Frequency and Period Average
measurements.
EXTERNAL GATE TIME: Continuously variable from loops
to Klsec, or one period of the input, whichever is longer.
EXTERNAL GATE DELW: 10~s + one period of the
input signal, maximum.
INTERNAL DELAY TIME: Variable from lOO@ to 10s~ in 45
increments. May be used in Period, Time Interval and Pulse
Width measurements.
EXTERNAL DELAY TIME: Continuously variable from loops
to >l hour.
EXTERNAL GATE/DELAY INPUT: Positive TTL signal via
rear panel BNC.
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TIME BASE
FREQUENCY: 1OMH.z.
AGING RATE: 55 x lo-‘/month.
TEMPERATURE: f5 x lo-! 0’ to 40°C, ref 25’C.
TCXO (with Model 7752 option)
FREQUENOI: l!&II-Iz
AGING RATE: <l x IO-‘/month.
TEMPERATURE: *I x 10-q 0 to 4O’C, ref 25’C.
LINB VOITAGE: < 1 x lO-’ for 10% change.
IEEE-488 INTERFACE
MULTILINE COMMANDS: DCL, LLO, SDC, Gm, GTL,
UNT, UNL, SPE, SPD.
UNILINE COMMANDS: IFC, RBN, EOI, SRQ, NN.
INTERFACE FUNCTIONS: SHl, AHl, T6, TEO, IA, LEO, SRl,
PPO, DCl, DTI, CO, El.
PROGRAMMABLE PARAMETERS: AI1 front panel controls
(except POWER) plus Reading Rate, Data Format, Trigger,
EOI, Terminator, Service Request, Self Test, Display, Stahu.
READING RATES: one shot, normal (3/second), fast
(ZYsecond), or dump (14O/second).
GENERAL
DISPLAY: Nine LED digits with decimal point and exponent.
BENCH READING RATES: One shot, or normal (3/second).
ARMING nRIGGER): Each channel is armed by it’s own
signal; or RESET button 01EXT ARMING input when in one
shot (HOLD) mode.
ARMING DELAY: 30~ in Frequency and Period Average;
lOas in Period, Tie Interval and Pulse Width.
EXTERNAL ARMING INPUT: positive edge ‘IX signal via
rear panel BNC.
EXTERNAL TIME BASE INPUT: lOMHz ‘ITL signal via rear
panel BNC
TIME BASE,OUT: 2V minimum @ MMHz, 1OODoutput resis-
tance, via rear panel BNC.
GATE: LED ,indicator lights when gate is open.
WARMUP: 2 hours to rated accuracy and stability
OPERATING TEMPERATURE: 0” to 4O”C, 0% to 80% relative
humidity
STORAGE TEMPERATURE: -25” to 65°C.
POWER: lO?-l25V or 2lO-250V (rear panel switch selected),
50-6OHz. 35VA max. 90-1lOV available.
DIMENSIONS, WEIGHT: l27mm high x 2l5mm wide x
359mm deep (5”~ 8’X’x 14r).
Net weight 3.5kg (8 lbs).
Specifications subject to change without notice.
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TABLE OF CONTENTS
SECTION l-GENERAL INFORMATION
1.1 INTRODUCTION. ........................................................................... l-l
1.2 MODEL775 FEATURES...................................................................... l-1
1.3 WARRANTY INFORMATION ................................................................. l-l
1.4 MANUAL ADDENDA ....................................................................... l-1
1.5 SAFETY SYMBOLS AND TERMS ............................................................. l-1
1.6 INSPECTION ............................................................................... l-2
1.7 USING THE MODEL 775 MANUAL .......................................................... l-2
1.8 ACCESSORIES .............................................................................. 1-2
SECTION Z-BASIC COUNTER/TIMER OPERATION
2.1 INTRODUCTION ........................................................................... 2-l
2.2 FRONTI’ANEL FAMILIARIZATICJI’J .......................................................... 2-4
2.2.1 Controls .................................................................................. 2-4
2.2.2 Terminals ................................................................................. 2-5
2.2.3 Display and Indicators ..................................................................... 2-6
2.2.4 TiltBail ................................................................................... 2-6
2.3 REAR PANELFAMILIARIZATION ............................................................ 2-6
2.3.1 Connectors and Terminals .................................................................. 2-6
2.3.2 Line Voltage Selector Switch ................................................................ 2-6
2.3.3 IEEE-488Address Switches ................................................................. 2-6
2.3.4 Line Fuse ................................................................................. 2-6
2.4 POWER-UP PROCEDURE .................................................................... 2-6
2.5 DISPLAYMESSAGES ........................................................................ 2-7
2.5.1 No Option Message ...................................................................... ...2- 7
2.6 CONTROL SELECTION ..................................................................... 2-8
2.6.1 Function .................................................................................. 2-8
2.6.2 Selecting GateTime ....................................................................... 2-8
2.6.3 User Gate Function ........................................................................ 2-9
2.6.4 Using Delay ............................................................................... 2-9
2.6.5 User Delay Function ...................................................................... 2-10
2.6.6 Selecting Measurement Rate ............................................................... 2-10
2.6.7 Selecting the Number of Displayed Digits. .................................................. 2-10
2.6.8 Input Condition Controls Setting., ......................................................... 2-11
2.6.9 Setting Trigger Levels ..................................................................... 2-11
2.7 ARMING.. ................................................................................ 2-12
2.7.1 Continuous Arming....................~ .................................................. 2.12
2.7.2
Front Panel Arming ....................................................................... 2-12
2.7.3 External Arming .......................................................................... 2-13
2.7.4 Alarm Conditions ......................................................................... 2-13
2.8 APPLICATIONS ............................................................................ 2-U
SECTION 3-IEEE-488 OPERATION
3.1 INTRODUCTION .. . .. . . . . . .. . . . . . . . . .. . . . . . . . .. . . . .._..._.................................. 3-l
3.2 BUS DESCRIPTION .. . . .. . . . . .. . . . . . . .._...............................................,,... 3-l
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TABLEOF CONTENTS
3.3
3.3.1
3.3.2
3.3.3
3.4
3.4.1
3.4.2
3.4.3
3.4.4
3.4.5
3.5
3.6
3.6.1
3.6.2
3.6.3
3.7
3.7.1
3.7.2
3.7.3
3.8
3.8.1
3.8.2
3.8.3
3.0.4
3.9
3.9.1
3.9.2
3.9.3
3.9.4
3.9.5
3.9.6
3.9.7
3.9.8
3.10
3.10.1
3.102
3.10.3
3.10.4
3.10.5
3.10.6
3.10.7
3.108
3.10.9
3.10.10
3.10.11
3.10.12
3.1o.u
3.10.14
3.10.15
3.10.16
3.10.17
3.11
3.11.1
3.11.2
3.11.3
3.u.4
3.:A
IEEE-488BUS LINES . . 3-2
Bus Management Lines.. .................................................................. 3-2
HandshakeLines .......................................................................... 3-2
Data Lines ................................................................................ 3-3
BUS COMMANDS .......................................................................... 3-3
Uniline Commands ........................................................................ 3-4
UniversalCommands ...................................................................... 3-4
Addressed Commands ..................................................................... 3-5
Unaddressed Commands .................................................................. 3-5
Device-Dependent Commands .............................................................. 3-5
COMMAND CODES ........................................................................ 3-5
COMMAND SEQUENCE. .............................................. .<................... 3-6
Addressed Command Sequence ............................................................ 3-6
Universal Command Sequence ............................................................. 3-6
Device-Dependent Command Sequence ..................................................... 3-6
HARDWARE CONSIDERATIONS ............................................................ 3-6
Typical Controlled Systems. ................................................................ 3-6 1~
BusConnections.. ........................................................................ 3-8
Primary Address Programming ............................................................ 3-10
SOFTWARE CONSIDERATIONS I .............................
: ............................... 3-10. ...
Controlled Interface Routines .............................................................. 3-10
HP-8 BASIC Statements .................................................................... 3-11
Interface Function Codes . . . 3-L?
Model 775 Interface Commandr ;
............................................................ 3-13
GENER,
AL BUS COMMAND PROGRAMMING .............................................. 3-13
REN (Remote Enable) ..................................................................... 3-13
IFC (Interface Clear) ..,,,...,,,,.......................................................... 3-14
LLO‘(Local Lockoui) .............................. .: ...................................... 3-14
GTL (Go To Local) ........................................................................ 3-14
DCL(Device Clear) ....................................................................... 3-15
SDC (Selective Device Clear) .............................................................. ,3-15
GET (Group Execute Trigger) .............................................................. 3-15
Serial Polling (SPE, SPD)
.................................................................. 3-16
DEVICE-DEPENDENT COMMAND PROGRAMMING ........................................ 3-16
Execute (X). .............................................................................. 3-19
Function(F) .............................................................................. 3-19
Channels A, d Coupling (AC, BC) ......................................................... 3-19’ ’
Channels A, B Attenuator (AA, BA) ....................................................... 3-20
Channels A, B Filter (AF, BF) ............................................................. 3-20
Channels A, B Slope (AS, BS). ............................................................ 3-20
Channels A, B Trigger Level (AL, BL) ...................................................... 3-20
Rate(S) ................................................................................. 3-21
Gate Time(G) ........................................................................... 3-22
Delay Time(W) .......................................................................... 3-22
Delay(I) .................................................................................
Displayed Digits(N) 3-23 I ...................................................................... 3-23
Triggering (T) ............................................................................ 3-23
EOI(K) ................................................................................. 3-23
SRQ Mode (M) and Serial Poll Status Byte Format .......................................... 3-24
Displayed Modes (D) ..................................................................... 3-26
Self-Test (J) ...............................................................................
3-27
READING FROM THE MODEL 775 ......................................................... 3-27
Data Control Commands (B) .............................................................. 3-28
Status Word (U)
.......................................................................... 3-29
Terminator (Y) ........................................................................... 3-30
Prefix(P) ................................................................................ 3-31
Dump Mode (53 Rate Mode) .............................................................. 3-31
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TABLEOFCONTENTS
.
3.12
FRONT PANEL PROGRAhJ.MING ...................................................................... 3-34
3.x2.1 IDDCError ......................................................................................... 3-34
3.12.2 IDDCO Error ....................................................................................... 3-34
SECTION G-PERFORMANCE VERIFICATION
ii
413
‘~ 4.4
4.5
4.5.1
4.52
‘4.5.3
.,- 4.5.4
4.5.5
4.5.6
a 4.5.7
. +,4.5.8
4.5.9
INTRODUCTION ........................................................................... 4-l
ENVIRONMENTAL CONDITIONS ........................................................... 4-l
RECOMMENDED TEST EOUIFMENT ........................................................ 4-l
INITIAL CONDITIONS -
... ...........................................................
VERIFICATION PROCEDURES ......................................................
Channels A, B and C Inputs Sensitivity. .............................................
Period Measurement Accuracy Check ...............................................
Period Averaged Measurement Accuracy Check ......................................
Tie Interval A-B Measurement Operation Check., .................................
Pulse A Measurement Operation Check.. ...........................................
Delay Operation Check ............................................................
External Gate Operation Check .....................................................
Arming Operation Check
............................................................
Model7752TCXO Accuracy Check ..................................................
SECTION 5-THEORY OF OPERATION
5.1
5.2
5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.3.5
5.3.6
5.3.7
* 5.4
5.4.1
5.4.2
5.4.3
54.4
5.4.5
INTRODUCTION ........................................................................... 5-l
OVERALL FUNCTIONAL DESCRIPTION ...................................................... 5-l
ANALOG CIRCIJITP.Y. ....................................................................... 5-3
Input Circuits A and B .................................................................... 5-3
Input C~cuitC ............................................................................ 5-3
1OMHz Standard Reference Oscillator ....................................................... 5-3
1OMHz ICXO Reference Oscillator .......................................................... 5-3
100MHzMultiplier ........................................................................ 5-3
Measurement Section ...................................................................... 5-4
Power Supply ............................................................................. 5-4
DIGITAL CIRCUITRY ....................................................................... 5-D
Microcomputer Block Diagram ............................................................. 5-13
Memory Mapping ........................................................................ 5-13
Address Decoding ........................................................................ 5-13
Keyboard/Display Interface ................................................................ 5-14
IEEE Interface ............................................................................ 5-14
SECTION 6-MAINTENANCE
INTRODUCTION .................................................................. 6-l
LINE VOLIAGE SELECTION ........................................................ 6-l
FUSE REPLACEMENT ....................................................................... 6-l
USING AN EXTERNAL TIME BASE,, ........................................................
6-2
MODEL 7751 CHANNEL C OPTION INSTALLATION ......................................... 6-3
MODEL 7752 TCXO OPTION INSTALLATION ................................................ 6-4
CALIBRATION ............................................................................. 6-5
Environmental Conditions. ................................................................. 6-5
Warm-Up Period .......................................................................... 6-5
Recommended Test Equipment ............................................................. 6-5
Calibration Procedure ...................................................................... 6-5
Multiplier Adjustment ..................................................................... 6-7
6.1
6.2
243
6.5
6.6
6.7
6.7.1
6.7.2
6.7.3
6.7.4
6.7.5
iii
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TABLEOF CONTENTS
6.7.6
6.7.7
6.7.8
6.7.9
6.7.10
6.8
6.9
6.10
6.10.1
6.10.2
6.10.3
6.10.4
6.10.5
6.10.6
6.10.7
6.10.8
6.10.9
Trigger Level Adjustment ................................................................... 6-7
Channels A and B Sensitivity Adjustment ................................................... 6-7
Inputs A and B Attenuator Compensation ................................................... 6-7
Tune Base Adjustment (Standard 5 PPM Tune Base) .......................................... 6-7
Time Base Adjustment (Optional 1 PPM Tie Base) .......................................... 6-7
SPECIAL HANDLING OF SEATIC SENSITIVE DEVICES ....................................... 6-8
DISASSEMBLY INSTRUCI’IONS. ............................................................. 6-8
TROUBLESHOOnNG ...................................................................... 6-10
Recommended Test Equipment. ............................................................ 6-10
Power-Up Self Diagnostics ................................................................. 6-10
Power Supply Checks ..................................................................... 6-10
Reference Oscillator and Clock Checks ...................................................... 6-11
Digital Circuitry and Display Checks ....................................................... 6-11
Signal Conditioning and Input Circuit Checks. .............................................. 6-11
Multiplier Circuit Checks .................................................................. 6-11
Trigger Level Checks ...................................................................... 6-11
Measurement Section Checks.. ............................................................ 6-11
SECTION 7-REPLACEABLE PARTS
Zl INTRODUCTION ............................................................................ 7-1
7.2 PARTSLIST.. ............................................................................... 7-l
7.3 ORDERING INFORMATION ................................................................. 7-l
7.4 FACTORY SERVICE .......................................................................... 7-1
7.5 SCHEMATIC DIAGRAM AND COMPONENT LOCATION DRAWINGS .......................... 7-l
iV
A APPENDIX.. ............................................................................... A-l
I INDEX ...................................................................................... I-l
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LIST OF ILLUSTRATIONS
2-l
2-2
2-3
2-4
2-5
3-l
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
5-l
5-2
5-3
5-4
5-5
5-6
5-7
5-8
6-l
6-2
6-3
6-4
6-5
7-l
7-2
7-3
7-4
7-5
7-b
7-7
7-8
7-9
7-10
Model775 Front Panel
....................................................................... 2-2
Model775RearPanel ........................................................................ 2-3
FallTime Measurement ..................................................................... 2-14
Using Delay to Measure Contact Dwell Time .................................................. Z-15
High Frequency Multiplexed Measurements ................................................... 2-15
IEEE Bus Configuration ................................... 3-2
IEEE Handshake Sequence ................................ 3-3
Command Codes ........................................ 3-7
System Types ............................................ 3-8
IEEE-468 Connector ...................................... 3-8
IEEE-488 Connections., ...................................
..,...
3-9
Rear Panel of Model 775 Showing IEEE connector ...........
.,..,.
3-9
Contact Assignments ..................................... 3-9
Typical IEEE-488 Bus Driver (One of 16) ................... 3-10
IEEE-488 Display Error Messages ..........................
.,....
3-35
Model775 Simplified BlockDiagram .......................................................... 5-2
Frequency A Measurement Block Diagram. .................................................... 5-6
Frequency B Measurement Block Diagram ..................................................... 5-7
Frequency C Measurement Block Diagram ..................................................... 5-8
Period A Measurement Block Diagram ........................................................ 5-9
Time Interval A-B Measurement Block Diagram .............................................. 5-10
Pulse Width Measurement Block Diagram. .................................................... 5-11
Microcomputer Block Diagram ............................................................... 5-12
Model 775Standard 5ppm Timebase .......................
Model 7751 Installation ...................................
Model 7752 Installation ...................................
Model 775 Calibration Adjustments ........................
Model 775 Exploded View ................................
Mother Board, Component Location Drawing .......................................
Mother Board, Schematic Diagram .................................................
Display Board, Component Location Drawing ........................................
Display Board, Schematic Diagram ..................................................
Model 7751, Component Location Drawing ..........................................
Model 7751, Schematic Diagram ....................................................
Model 7752, Component Location Drawing ..........................................
Model 7752, Schematic Diagram ....................................................
5 ppm Oscillator, Component Location Drawing. .....................................
5 ppm Oscillator, Schematic Location Diagram .......................................
6-2
b-3
b-4
6-6
6-9
7-11
7-13
7-26
7-27
7-29
7-30
7-31
7-32
7-33
7-34
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LIST OF TABLES
2-l Gate/Delay Determination. ................................................................... 2-8
2-2 Alarm Condition
............................................................................. Z-13
3-l
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-D
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
IEEE-488BusCommand Summary ............................................................ 3-4
Hexadecimal and Decimal Command Codes ....................... ........................... 3-h
Typical Addressed Command Sequence .......................................................
3-b
Typical Device-Dependent Command Sequence ................................................ 3-6
IEEE Contact Designations ................................................................... 3-9
HP-85 IEEE-488 BASIC Statements ........................................................... 3-11
Model 775 Interface Function Codes,, ........................................................ 3-12
IEEE Command Groups ..................................................................... 3-13
General Bus Commands ........................................................... ........ 3-13
Default Conditions (Status Upon Power Up or After SDC or DCL)
.............................. 3-15
Device-Dependent Command Summary ...................................................... 3-17
Rate Commands ............................................................................ 3-21
Gate/Delay Time Predetermined Value., ...................................................... 3-23
SRQ Mask Commands ...................................................................... 3-24
SRQ Mask Legal Commands.. .............................................................. 3-25
Status Byte Interpretation ............................... ................................... 3-26
Data String Format ......................................................................... 3-28
Prefixes. ............................................... , ................................. 3-2’)
Status Word Format .................................... . ................................... 3-30
DumpMode Specifications........................................................: .......... 3-33
Dump Ouput Mode Result Calculation ... .............. , ................................... 3-34
4-l Recommended Test Equipment for Performance Verification ..................................... 4-l
5-l Model775 Memory Mapping ................................................................ 5-13
6-l Line Fuse Selection ........................................................................... b-l
6-2 Recommended Test Equipment for Calibration ............ .................................... 6-5
6-3 Static Sensitive Device ....................................................................... 6-8
6-4 Recommended Minimum Test Equipment for Troubleshooting .................................. 6-K)
6-5 Power Supply Checks ....................................................................... b-11
6-6 Reference Oscillator and Clock Checks .............. ........................................ b-12
6-7 Digital Circuitry and Display Checks .. ............. ........................................ 6-12
6-8 Signal Conditioning Checks .............. .................................................. b-13
6-9
Input Circuit Checks ........................................................................ 6-U
6-10 Multiplier Circuit Checks .................................................................... 6-13
6.11 Trigger Level Circuit Checks.. ............................................................... b-14
6-12 Measuring Section Circuit Checks .......... ................................................. 6-14
7-l
7-2
7-3
Mother Board, Parts List ..................................................................... 7-2
Display Board, Parts List .................................................................... 7-25
Model 775 Mechanical Parts List ...... . ................................................. 7-35
vi
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GLOSSARY OF TERMS
Time Base Uror4ime base error is the maximum frac- lklgger Timing Error-
tional frequency change in the time base frequency due
to all errors (e.g. aging, temperature, line voltage). 35mV 35mV
+
ligger Ermr-
q ei2 + en2
Input Slew Rate at Trigger Point
Input Slew Rate at Start Input Slew Rate at Stop
Trigger Point Trigger Point
External Arming (Wgger) Delay-External arming delay
is the time from the positive going slope of the arming
signal to the internal gate open signal.
Where: External Gate Delay-External gatedelay is the time from
ei is the RMS noise voltage of the counter’s input channel the positive going slope of the gating signal to the inter-
(25OhVtypical). nal gate open signal.
en is the RMS noise of the input signal for lZ0MHz
bandwidth.
LSD-Unit value ot%eleast significant digit. Calculations
should ba rounded asfollows: 1to 1.3Hz becomes IHz,
l.hwec to liinsec becomes IOnsec, etc.
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SECTION 1
GENERAL INFORMATION
1.1 INTRODUCTION
The Keithley Model 775Programmable CouirterlTimer is
a nine digit, microcomputer based, fully programmable,
universal counter/timer. The Model 775 measures with
high resolution the following parameters:
l Frequency A
l Frequency B
l Frequency C
l Period
. Period Averaged
l Time Intervals A - B
l Pulse Width (positive or negative) A
The Model 775 has an 14mm (0.56in.) LED display. The
display consists of 9 digits with an additional digit for ex-
ponent. The built-in interface makes the instrument fully
programmable over the IEEE-488 bus.
The Model 775contains a programmable trigger level that
allows additional flexibility in measurements over the bus
(e.g. measuring rise and fall time with trigger points other
than 10%and 90%). Gate time is programmed in 46steps
from 100psecto 1Osecor external from the front panel or
over the bus.
1.2 MODEL 775 FEATURES
Dual Channel Capability-Dual channel capability with
two similar channels up to ‘IZOMHz.
Full Programmability-Full programmability of all func-
tions and modes including different SRQmasksand chan-
nel selection.
High Frequency Option-H&option adds athird measure-
ment channel for frequencies up to 1GHz.
High Resolution-A 1OOMHzclock rate, along with the
latest technique in frequency counting (reciprocal techni-
que), provides the high resolution of 8digits/second or VIZ
out of a 1OOMHzinput signal.
Trigger Delay Channel B-This feature is important for
some channel A - B time measurements.
True DC Coupling-Allows the Model 775 to do channel
A - B time measurements.
Reciprocal Technique-This counting method provides ad-
vantages over all traditional counters from DC up to the
clock frequency (100MHz). The constant relative resolu-
tion (8 digits/second independent of input frequency)
makes it even more useful for low frequency applications.
1.3 WARRANTY INFORMATION
Warranty information may be found on the inside front
cover of this manual. Should it become necessary to exer-
cise the warranty, contact your Keithley representative cur
the factory to determine the proper course of action.
Keithley Instruments maintains service facilities in the
United States, United Kingdom and throughout Europe.
Information concerning the application, operation or ser-
vice of your instrument may bedirected to the applications
engineer at any of these locations. Check the inside front
cover for addresses.
1.4 MANUAL ADDENDA
Information concerning improvements or changes to the
instrument which occur after the printing of this manual
will be found on an addendum sheet included with this
manual. Be sure to review these changes before attemp-
ting to operate or service the instrument.
1.5 SAFETY SYMBOLS AND TERMS
The following safety symbols and terms are used in this
manual or found on the Model 775.
Then symbol on the instrument denotes that the user
should refer to the operating instructions in this manual.
The WARNING used in this manual explains dangers that
could result in personal injury or death.
l-l
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The CAUTION used in this manual explains hazards that
could damage the instrument.
1.6 INSPECTION
The Model 775was inspected both mechanically and elec-
trically beforeshipment. After unpacking all the items from
the shipping carton, check for any obvious signs of
physical damage that may have occurred during transit.
Report any damage to the shipping agent. Retain and use
the original packing materials in case reshipment is
necessary. The following items are shipped with every
Model 775.
Model 775 Programmable Counter/Timer
Model 775 Instruction Manual
Additional accessories as ordered.
If an additional Instruction Manual is required, order the
manual package (Keithley part number 775-901-00).The
manual package includes an instruction manual and any
applicable addenda.
1.7 USING THE MODEL 775 MANUAL
l Section 1 contains general information about the
instrument.
l Section 2contains detailed operating information on us-
ing the front panel controls and rear panel terminals.
l Section 3contains information necessary to operate the
Model 775 over the IEEE-488 bus.
l Section 4 contains performance verification procedures
for the instrument. This information is helpful if you
wish to verify that the instrument is operating in com-
pliance with stated specifications.
l Section 5 contains a description of operating theory.
l Section 6contains information for servicing the instru-
ment. This section includes information on line voltage
selection, fuse replacement, adjustments and
troubleshooting.
l Section 7 contains replacement parts information.
1.8 ACCESSORIES
The following optional accessoriesare available to enhance
the Model 775 capabilities.
Model 1019AFixed RackMount-The Model 1019Ais asta-
tionary rack mount kit that allows the Model 775 to be
mounted in a standard 19 inch rack.
Model 1019s Slide Rack Mount-The Model 10195 is a
sliding rack mount kit that allows the Model 775to be rack
mounted with the added feature of sliding the instrument
forward for easy accessto the rear panel and top cover.
Model 7007 IEEE-488 Shielded Cables-The Model 7007
connects the Model 775to the IEEE-488bus using shield-
ed cablesto reduce electromagnetic interference (EMI). The
Model 7007-1is one meter in length and has an EM1shield-
ed IEEE-488connector at each end. The Model 7007-2is
identical to the Model 7007-1,but is two meters in length.
Model 7008IEEE-486Cables-The Model 7008connects the
Model 775to the IEEE-488bus. The Model 7008-3is 0.9m
(3 ft.) in length and has a standard IEEE-488connector at
eachend. The Model 7008-6cable is identical to the Model
7008-3,but is 1.8m (6 ft.) in length.
Model 7051BNC to BNC Cable--The Model 7051is 1.5m
(5 ft.) in length and is terminated on eachend with aBNC
Ph%
Model 77511GHz Channel C Option-The Model 7751is
a factory-installed option which provides a third channel
(C) for measuring frequencies between 50MHz and IGHz.
Model 7752 TCXO-High Stability Crystal Oscillator
Option-The Model 7752 is a factory-installed TCXO-high
stability crystal oscillator that offers improvement over the
standard time base, relative to aging and temperature.
Model 7754-3BNC to Alligator Cable-The Model 7754-3
is 0.9m (3ft.) in length and is terminated on one end with
a BNC plug and on the other with two alligator clips.
Model 77555012Feedthrough Termination-Ihe Model 7755
is a BNC tb BNC adapter for terminating RG 58 cable in
its characteristic impedance. VSWR <l.l, DC -250MHz.
SNC BNC
PLUG JACK
l-2
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SECTION 2
BASIC COUNTER/TIMER OPERATION
2.1 INTRODUCTION
ed is a brief description of each control, terminal and
indicator.
Model 775 operation is divided into the two general
categories: basicbench operation, and IEEE-488operation.
Basicbench operation which is covered in this section, con-
sists of using the Model 775 to perform basic frequency
and time measurements. IEEE-488programming can also
be used. These aspects are covered in detail in Sections
3 and 4. A layout of the front and rear panels of the Model
775 are shown in Figures 2-l and 2-2 respectively, includ-
NOTE
Any front panel button push or IEEE device-
dependent command (seeSection 3) will causethe
measurement to restart, which will affect, for ex-
ample, a measurement of the time from channels
A to B.
2-1
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OPERATION
q POWER ON/OFF-Turns the unit on or off. El GATE/DELAY TIME CROUP-
q FUNCIXON GROUP- . GATE/DELAY TIME buttons control: time gate is
l FREQ button toggles measurement between frequency open, delay of gate closure and number of digits
displayed.
at channel A and frequency at channel 8.
l PERIOD button toggles measurement b&./em the
l These buttons increment or decrement the displayed
value by one step.
period A and period average A.
l TIME button toggles measurement between the time El LOCAL-Enables front panel operation.
interval A-B and pulse width of A.
l MODE button places instrument in either the hold,
q RESET-Resets display to initiate new measurement cy.
delay, both hold and delay, or normal mode. cle during normal or hold mode operation.
El CHAN C-Measures frequencies from 50MHz to 1GHz El TERMINALS-
through channel C.
l CHAN A used when making frequency and time
El measurements. INPUT SEITING GROUP- * WAN B used when making frequency and time A-B
l DC/AC button toggles instrument between AC and DC measurmlents.
coupling of the input signal. . CHAN C used when making high frequency measure-
* SLOPE button toggles instrument between the positive ments up to 1GHz with a 500 input impedance (7751
or negative edge trigger. option). The shell is connected to chassis ground as
l A’lTEN button tot&sinstmment between the xl and indicated by the I symbol.
x10 input attenuZon.
l FUR button toggles filter between on and off. El DISPW AND INDICATORS-
* LEVEL buttons select the threshold point on a signal
l Display consists of a nine digit mantissa and a single
that the instrument will trigger. digit exponent.
l
El Ran e indicator consist of Hz, SEC, V. Hz is on dur-
DISPLAY MODIFY GROIJP- ing te qwncy measurement. SEC is on during time
. GATE/DELAY button modifies display horn normal fre- and ,period measurements. V is on when TRIGGER
quency (or time reading) to gate time or delay time. LEVEL button is pressed.
l TRIGGER LEVEL button modifies the display to show
l GATE indicator blinks at a rate proportional to gate
trigger level of both channels A and B. time.
l IEEE status indicators select either remote. talk or listen
when programming over IEEE-488 bus.
Figure 2-1. Model 775 Front #Panel
2-2
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OPERATION
El
CONNECrORS AND TRRMINALS- El LINE VOLTAGE SELEOR switch selects the line
l AC receptacle connects to a three wire line cord voltage that the unit will operate on.
which provides connection to the line voltage.
l IEEE-483 connector is used to connect the instrument El IEEE-488 address switches set the primary address for
to the IEEE-488 bus. IEEE interface functions are IEEE-488 bus operation.
marked above the connector.
l TRIGGER LEVEL OLPTPLJT connections are used to El LINE FUSE provides protection on the AC power line
connect the DC voltage level from the trigger circuits input.
to an external Dh4M or osciIloscope. DC output range
is marked above the connector.
l CLOCK connactor is used to output the internal clock
as a reference to another instrument or to use an ax-
ternal clock as the Model 775’s time base.
. EXT ARMING & GATE DELAY connector is used to
receive one of three signals: arming pulse, external
gate signal or external delay pulse.
Figure 2-2. Model 775 Rear Panel
2-3
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OPERATION
2.2 FRONT PANEL FAMIC1ARIZATION
The front panel layout of the Model 775is shown in Figure
2-1.The front panel is generally divided into three sections:
controls, terminals, and display and indicators. The follow-
ing paragraphs describe the purpose of eachof these items
in detail.
2.2.1~ Controls
All front panel controls except POWER are momentary
contact switches. Many controls include an annunciator
light to indicate the selected configuration. The controls
arecolor coded into functional groups for easier operation.
Front panel controls may be divided into the following
functional groups: Function, Input Setting, Display Modify
and Gate/Delay Time.
POWER-The POWERswitch controls the AC power to the
instrument. Depressing and releasing the switch once
turns the power on. Depressing and releasing the switch
a second time turns the power off.
Function GrouP4he four FUNCTlON buttons control the
type of measurement, Each button is used to select one
of two functions.
FREQ-The FREQbutton places the instrument in frequen-
cy measurement mode. Pressing the FREQ button once
turns the A indicator on; indicating the instrument is set
for the frequency A mode. Pressing the button a second
time, turns the B indicator on; indicating the instrument
is setfor the frequency B mode. Pressing of the FREQbut-
ton toggles the measurement between the frequency at
channel A and frequency at channel B modes.
PERIOD-The PERIOD button places the instrument in
period measurement mode. Pressing the PERIOD button
once turns the A indicator on; indicating the instrument
is in the period A mode. Pressing the PERIOD button a
second time, turns the AVG A indicator on; indicating the
inetrument is in the period average A mode. Pressing of
the PERIOD button toggles the measurement between the
period A and period average A.
TIME-The TIME button setsthe Model 775up to measure
the time interval between channel A and 8. Pressing the
TIME button once turns the A-B indicator on; indicating
the instrument is in the time interval A-B mode. Press-
ing the button a second time, turns the PLS A indicator
on; indicating the instrument is in the pulse A mode.
l’ressi,ig of the TIME button toggles the measurement bet-
ween the time interval, A-B and pulse width of A.
MODE-Press the MODE button once to place the lnstru-
ment in the hold mode. Press the RESETbutton to clear
the display and take a reading. The reading will be held
on the display until the RESET button is pressed again.
Pressing the MODE butt.on a second time, places the
Model 775in the delay mode of operation; the instrument
holds off closure of the gate for the selected delay time.
Pressing the MODE button a third time places the instru-
ment in both the hold and delay modes. Pressing of the
MODE button a fourth time turns the indicators off: and
places the instrument in the normal mode of operation.
NOTE
The delay ,mode is disabled in the frequency and
period averaging modes.
FREQ C--The: FREQ C button allows the Model 775 to
measure frequencies from 50MHz to lGHz on channel C.
Pressing the FREQ C button turns the C indicator on; ln-
dicating the instrument is set to make high frequency
measurements on channel C. If the Model 7751Channel
C option is not installed, a ‘no C OPY message will be
displayed for two seconds.
Input Setting Group-The six WAN A pushbuttons con-
trol input attenuation, coupling, slope, trigger level and
high frequency noise suppression. The six CHAN B
pushbuttons are functionaly identical to the CHAN A
buttons.
DC/AC-The DC/AC button selects either the AC or DC
coupling mode. In default position, the instrument is in
the DC coupling mode. Pressing the DC/AC button turns
the AC indicator on; indicating the instrument is in the
AC coupling mode. Pressing of the DC/AC button toggles
the instrument between AC and DC coupling of the in-
put signal.
SLOPE-The $LQPE button selects the slope that the
Model 775 will trigger on. In default position, the instru-
ment triggers on apositive going edge.Pressing the SLQPE
button turns the ” 1 ” indicator on; indicating the in-
strument will trigger on a negative going edge. Pressing
of the SLOPE button toggles the instrument between the
positive or negative edge trigger.
ATTEN-The ATTEN button controls the attenuation of the
input signal. In default position, the signal will not be at-
tenuated. Pressing the ATTEN button turns the x10 in-
dicator on; indicating that the instrument will attenuate
the signal by Ill. Pressing of the ATTEN button toggles the
instrument between the xl and xl0 input attenuation. Note
that changing attenuation changes the trigger level. (e.g.
1V trigger on xl goes to lOV on x10).
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OPERATION
FLTR-The FLTR button limits high frequency noise to
about 1OOkHzthrough alow-pass filter installed at the in-
put terminal. In default position, the low-pass filter is off.
Pressing the FLTRbutton turns the FLTRindicator on; in-
dicating that the low-pass filter is on. Pressing of the FLTR
button toggles the filter between on and off.
LEVEL-The LEVEL buttons select the signal voltage level
that will trigger the instrument (e.g. start and/or stop the
measurement interval). Pressing the ‘I button decrements
the level by one step. Pressing the A button increments
the level by one step.Eachstepis 1OmVon the xl attenuator
setting or 1OOmVon the x10attenuator setting. Holding the
LEVEL A or v button in for more than one second, causes
the trigger level to continuously move up or down respec-
tively. Holding the LEVEL A and v buttons in at the same
time, causes the instrument to jump to the preset posi-
tion O.OOV(or OO.OV).
Display Modify Group-The two pushbuttons in the
display modify group modify the display from normal fre-
quency (or time reading) to another reading such as trig-
ger level, gate time, delay time or displayed number of
digits.
GATE/DELAY-The GATE/DELAY pushbutton has two
functions: When instrument is in the frequency or period
averaged functions, this button modifies the display to
display the time that the gate remains open to complete
one cycle. When instrument is in the time interval, period
A or pulse A function, this button modifies the display
to show the time that the closure of the gate is delayed
after its opening. Press GATE/DELAY to exit.
TRIGGER LEVEL-The TRIGGER LEVEL button may be
used to modify the display to show the trigger level of both
channels A and B. Pressing !he TRIGGER LEVEL button
turns the indicator above the button on, indicating that
the instrument is in the trigger level display mode. The
display will contain two sets of readings (three digits for
each channel). The three digits to the left on the display
concern channel A, while the three digits to the right on
the display concern channel B. Use CHAN A or CHAN
B Level buttons to modify the values. Press TRIGGER
LEVEL to exit.
Display Function-The display function allows the user to
select the maximum number of most significant digits
which are to be displayed. In the normal operating mode,
the instrument will display amaximum of nine digits. The
minimum number of digits displayed is three. To access
the display function press simultaneously the
GATE/DELAY and TRIGGER LEVEL buttons. Select the
number of digits to be displayed by pressing the
GATE/DELAY TIME A or v button to increment or decre-
ment the display. To resume normal operation, simply
press any other button on the front panel. The instrument
will display its measurements with the preselected number
of digits.
GATE/DELAY TIME-The two GATE/DELAY TIME buttons
control: the time that the gateis open from 100~s~ to 1Osec
in 46 steps; the delay of the gate closure from 100psecto
1Osecin 46 increments; and the number of digits to be
displayed in increments of seven.
GATE/DELAY A, V-Each time the A button is pressed,
the gate or delay increments one step. Each time the v
button is pressed, the gate or delay decrements one step.
If A or v button is held in for more than one second, the
instrument will continuously increment or decrement. If
the A and v buttons are held in at the same time, the
instrument will jump to a preset position of laec delay time
or nine digits displayed numbers.
User Gate/Delay Function-Information on accessing this
function will be given later in this chapter.
LOCAL--Pressing the LOCAL button when the instru-
ment is in remote operation (but not in remote (local)
lockout condition), will place the instrument in local opera-
tion. Pressing this button when the instrument is already
in local operation will have no effect on the instrument.
RESET-Pressing the RESETbutton during normal opera-
tion will reset the display and initiate anew measurement
cycle. When the instrument is in the hold mode of opera-
tion, pressing the RESET button clears the display and
arms the instrument for the next measurement.
2.2.2 Terminals
The terminals are used to connect the Model 775 to the
signal to be measured.
Channel A-The CHAN A terminal is used when making
frequency and time measurements.
Channel B-The CHAN B terminal is used when making
frequency and time A-B measurements.
Channel C-The CHAN C terminal is used for high fre-
quency measurements up to 1GHz with a 5Ofl input im-
pedance Although this terminal is always installed, the
internal circuitry needed to operate this function is optional
and may not be installed. BNC shell is connected to chassis
ground as indicated by the I symbol.
2-5
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