Krohn-Hite 522 User manual

Model 522
Manual/Remote Controlled (GPIB Programmable)
DC Voltage/Current Calibrator
Operating Manual

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PROGRAMMABLE
VOLTAGE
DC CURRENT CALIBRATOR
Model 522
Serial No.______________

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522
OPERATORS
MANUAL
Copyright © 1999
Electronic Development Company
Division of KROHN-HITE
15 Jonathan Drive Unit 4
Brockton, Massachusetts 02301
E-mail: [email protected]
www.krohn-hite.com
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in
any form by any means, electronic, mechanical photocopying, recording, or otherwise, without the prior written
permission of Electronic Development Company
Printed in U.S.A.
Version 3.27
Revised January 2003
Information furnished in this manual is believed to be accurate and reliable. However, no responsibility is assumed
by Electronic Development Company for its use; nor for any infringements of patents or other rights of third
parties which may result from its use.

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522 TABLE OF CONTENTS
SECTION TITLE
iList of Drawings
ii Limited Warranty
iii Factory Service Request and Authorization
iv Packing Suggestions
I DESCRIPTION AND SPECIFICATIONS
1.1.0 General Description
1.2.0 Features and Applications
1.2.1 Features
1.2.2 Applications
1.3.0 Output Specifications
1.4.0 General Specifications
1.5.0 Mechanical Specifications
1.6.0 General Information
II INSTALLATION
2.1.0 Mounting
2.2.0 Mating Connectors
2.3.0 IEEE 488 Cables
2.4.0 AC Power Input Considerations
2.5.0 Thermal Considerations
III OPERATION OF THE INSTRUMENT
3.1.0 Front Panel Controls
3.2.0 Front Panel Indicators
3.3.0 Output Connections
3.4.0 Remote Programming with the IEEE 488 Bus
3.5.0 Remote Programming with the RS-232 Option
3.6.0 Voltage Compliance Limit Control
3.7.0 Operating Voltage Conversion
IV THEORY OF OPERATION
4.1.0 Introduction
4.2.0 Control Board
4.3.0 Microprocessor Circuits
4.4.0 Digital Board IEEE 488 Logic
4.5.0 Digital to Analog Converter
4.6.0 Output Amplifier
4.7.0 Output Switching
4.8.0 Range Logic

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TABLE OF CONTENTS (Continued)
V CERTIFICATION AND TESTING
5.1.0 Recommended Equipment
5.2.0 Calibration Procedure
VI OPTIONS - (If Installed)
6.1.0 1 Volt Option RA-7
6.2.0 Calibration. of the RA-7 option.
VII PARTS LIST
7.0.0 Replacement Parts for Model 522
NOTE: Errata and addendum (if any) will appear in the back of this manual.

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522 MANUAL
LIST OF DRAWINGS
DESCRIPTION DRAWING #
MPU Flow Chart A-4634 Rev. A
IEEE-488 Logic Schematic A-4610 Rev. D
1V Range Board Schematic - Option RA-7 A-4636 Rev. F
1V Range Board Layout - Option RA-7 A-4817 Rev. F
System Block Diagram B-4633 Rev. A
Power Supply Schematic B-4615 Rev. B
522 Control Board Schematic (Displays ) B-4819 Rev. A
522 Control Board Schematic (Switches) B-4820 Rev. A
MPU Board Schematic B-4763 Rev. A
DAC Schematic C-4614 Rev. C
Range Logic Schematic B-4611 Rev. B
Output Amplifier Schematic B-4613 Rev. B
Output Switching Schematic B-4612 Rev. C
522 Control Board Layout B-4822 Rev. A
MPU Board Layout B-4765 Rev. A
Motherboard Layout B-4630 Rev. I
Motherboard Layout B-4631 Rev. I
Reference Drawing 930727A
Front or Rear Terminal Connector CB-4718

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LIMITED WARRANTY
The ELECTRONIC DEVELOPMENT COMPANY (E.D.C.) warrants to the original
purchaser each instrument manufactured by them to be free from defects in material and
workmanship. This warranty is limited to servicing, repairing and/or replacing any instrument or
part thereof returned to the E.D.C. factory for that purpose in accordance with the instructions set
forth below; and furthermore to repair or replace all materials, except tubes, fuses, transistors and
other semiconductor devices which shall within ONE YEAR of shipment to the original purchaser
be returned to the E.D.C. factory and upon examination be deemed defective.
E.D.C. instruments may not be returned to the factory under the terms of this warranty
without the prior authorization of the E.D.C. Service Department. All instruments returned to
E.D.C. for service hereunder should be carefully packed and shipped. All transportation charges
shall be paid by the purchaser.
EDC reserves the right to discontinue instruments without notice and to make changes to
any instrument at any time without incurring any obligation to so modify instruments previously
sold.
This warranty is expressly in lieu of all other obligations or liabilities on the part of EDC.
No other person or persons is authorized to assume in the behalf of EDC any liability in the
connection with the sale of its instruments.
CAUTION:The instrument you have purchased is a precision instrument
manufactured under exacting standards. Any attempts to repair, modify or
otherwise tamper with the instrument by anyone other than an EDC employee or
authorized representative may result in this warranty becoming void.

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FACTORY SERVICE REQUEST
AND
AUTHORIZATION
WARRANTY SERVICE
Instruments may be returned only on prior authorization. Please
obtain a RETURN AUTHORIZATION NUMBER either directly from the
factory or from an authorized E.D.C. Representative. (See General
Information below.)
CHARGEABLE REPAIRS
If requested, an estimate of charges will be submitted prior to
repairs. We suggest that you request a RETURN AUTHORIZATION NUMBER
to facilitate handling.
GENERAL INFORMATION
A) Please provide the following information in order to expedite
the repair:
1) Indicate MODEL
2) Serial Number
3 Complete description of the trouble:
Symptoms, measurements taken, equipment used, lash-up
procedures, attempted repairs, suspected location of
failure and any other pertinent information.
B) Freight Charges must be PREPAID.
C) The RETURN AUTHORIZATION NUMBER should be noted on your
documentation.
D) See Packing Suggestions - next page.

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PACKING SUGGESTION
Although your E.D.C. instrument is built for laboratory, production environment and some field
environment, it is NOT ruggedized. Therefore ...
1. Be sure the carton is STRONG enough to carry the weight of the instrument, e.g. use
double wall corrugation.
2. Be sure the carton is LARGE enough to allow for sufficient packing material, e.g., at least
2 inches all around the instrument. The packing material should be able to be compressed
and then return to its approximate original volume.
3. For better handling, the shipment should always be by AIR FREIGHT (expect for short
distances). You might use either UPS "blue label" or common air freight carrier, second
day air.
Please do not bounce it across the country in a truck. It may not hurt it, but it certainly is
not going to do a laboratory instrument much good.
4. QUESTIONS? Just contact us. We will be pleased to help you.

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SECTION I
1.0.0 DESCRIPTION AND SPECIFICATIONS
1.1.0 General Description
1.1.1 The EDC Model 522 is a microprocessor controlled enhanced version of the field proven Model
521. An industry standard 6500 series microprocessor has been incorporated to improve the
reliability, and versatility of the instrument.
1.1.2 The Model 522 Programmable DC Voltage Standard is a highly versatile reference source,
designed to meet the needs of computer systems, production line testing, automated calibration,
and standards laboratories.
1.1.3 The instrument has a specified accuracies, that are traceable through a bank of saturated standard
cells to the U. S. National Institute of Standards and Technology.
1.1.4 Resolution of each range, in each function, is 1 part per million.
1.1.5 The instrument is a highly accurate reference which can be used for calibration of digital
voltmeters, analog meters, semiconductor analyzing systems, analog references for computers,
analog-to-digital converters, telemetry and data acquisition systems, and wherever a stable source
is required.
1.1.6 The variable, constant current mode is designed for use in calibration and simulation of strain
gages and other transducers.
1.1.7 There are no adjustments made during normal operation; the trims are made during calibration
and are described in the calibration procedure.
1.1.8 The circuitry is completely solid state made of discrete, hybrid and/or integrated circuits packaged
on etched glass circuit boards. These are proven circuits, using derated components to insure long
life and maximum reliability.
1.1.9 The instrument is overload and short-circuit proof, and is fully operational in normal
environmental conditions.
1.1.10 The Standard Source will drive a short circuit indefinitely without damage to the instrument, and
will recover to rated specifications in less than 100µs.

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1.2.0 Features and Applications
1.2.1 Features:
Accuracies based on one full year calibration cycle and conservatively specified by using the "Limit
of Error" (or Worst Case) methods.
E Mode: ±(0.002% of setting + 0.0005% of range + 2 µV)
I Mode: ±(0.005% of setting + 200 nA)
Programming: IEEE-488 (GP-IB) and local/manual control. (Note):Operator has control of
local/remote mode i.e., shutdown not required to re-establish "local" control.)
3 Voltage ranges (1 ppm resolution or 6 decades)
± 100 Vdc resolved to 100 µV
± 10 Vdc resolved to 10 µV
± 100 mVdc resolved to 0.1 µV
2 Current ranges (1 ppm resolution or 6 decades)
± 100 mAdc resolved to 0.1 µA
± 10 mAdc resolved to 0.01 µA
(Note: 100 Vdc Compliance with variable control.)
Floating output. Optically isolated between analog output and digital input lines.
True bipolar control with balanced zero.
Magnitude is maintained during polarity changes, and scaled on function changes and range
changes in the manual mode. i.e., this eliminates the requirement of re-entering the magnitude.
A "crowbar", or short circuit, of the output may be selected.
Alpha-numeric dot matrix display, for ease of reading and less digital noise on the
analog output.
1.2.2 Applications:
Calibration of DVMs, DMM, meters, chart recorders, A/D converters, ATE, monitors,
controllers, logging systems, etc.
Simulation of thermocouple and strain gages. (4 to 20 mA and 10 to 50 mA) and
other transducers.
NOTE: Compliance voltage from 1V to 100 Vdc. Compliance limits are selectable.
Linearity check of amplifiers and function modules.

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1.3.0 Output Specifications
1.3.1 Voltage Mode
Range 100 mVdc 10 Vdc 100 Vdc
(Full Scale) ±111.111 0 mVdc ±11.111 10 Vdc ±111.111 0 Vdc
Resolution 100 nV 10 µV 100 µV
(1 ppm)
Compliance EMF into 100 mA 100 mA
Current 1 meg Ohms
Output 20 Ohms 10 mOhms 10 mOhms
Impedance
Accuracy (Basis for accuracy statement):
The Accuracy Statement is based on the "Limit of Error" (or "worst case") method. All other
specifications noted hereafter, which effect accuracy, e.g., line, load, temperature, and drift
changes are included in the accuracy statement. Thus, all other specifications are listed as
*non-Additive.
±(0.002% of setting + 0.0005% of range + 2 µV)
Note: The "+ 2 µV" specified above applies primarily to the 100 mV range where measurements
at these low levels should be stated conservatively. It becomes insignificant on the higher ranges.
Note: The accuracy statement above is based on the "Limit of Error"method and is VALID FOR
ONE YEAR calibration cycles. The "Limit of Error" accuracy may be increased to tighten
tolerances by:
A) Shortening re-calibration cycle, i.e., more frequently than the suggested 1 year cycle.
and/or
B) Elimination of "worst case" conditions by implementing carefully monitored, standards
laboratory procedures.
Stability: (*non-additive)
8 hrs: ±0.00075%; 24 hrs: ±0.001%
90 days: ±0.0015% 1 yr: ±0.002%
Line & Load Regulation: (*non-additive)
±0.0005% No load to full load for a ±10.0% line fluctuation

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1.3.2 Current Mode
Range 10 mAdc 100 mA
Full Scale ±11.111 10 mAdc ±111.111 0 mAdc
Resolution (1 ppm) 10 nA 100 nA
*Compliance Voltage 0 - 100 Vdc 0 - 100 Vdc
Output Conductance 0.1 µs 0.1 µs
*Note: Voltage Compliance Limit Control - See para 3.6.0.
Accuracy: (See definitions under Voltage mode)
±0.005% of setting + 200 nA
Stability:(*non-additive)
8 hrs: ±0.00075% 24 hrs: ±0.001%
90 days: ±0.0015% 1 year: ±0.002%
Line & Load Regulation:
±0.0005% from short circuit to full compliance and/or for a ±10% line fluctuation.
1.4.0 General Specifications
Isolation:
Power Transformer to analog output: 2.5 x 104M Ohms, 300 pF Control logic to analog
output; optically isolated. 10 9 Ohms, 130 pF, 500 Vdc
Temperature Coefficient:
Ambient: ±0.0005% / º C
Operating Limit: ± 0.001% / º C
Switching and Settling Times:
Step Changes: 5 ms
Range Changes: 300 ms
Protection:
Voltage mode: Short-circuit and overload protection.
Current mode: Open-circuit protection.
Front panel enunciator and alpha-numeric display will indicate malfunction condition.
Warm-up Time: 1 hour to rated accuracies

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1.4.1 Noise & Ripple: The following specifications are furnished in detail so the user can have complete
confidence in the results of their tests.
PEAK-TO-PEAK (Typical Performance)
IMPROVED NOISE SPECIFICATIONS
0.1Hz To: 100Hz 1kHz 10kHz 100kHz
100mV range 10µV 15µV 35µV 45µV
10V range 30µV 50µV 100µV 150µV
100V range 300µV 400µV 600µV 600µV
1.5.0 Mechanical Specifications
Power Requirements: 70 W; 115 V or 230 Vac ±10%; 50/60 Hz
See paragraph 3.7.0 for power line voltage changing instructions.
Temperature:
Calibration Temperature: 23 º C ±1 º C
Ambient Temperature: 20 º C to 30 º C
Operating Limit: 10 º C to 50 º C
Storage Temperature: -40 º C to 85 º C
Dimension: W 19 x H 3.5 x D 21 inches; W 480 x H 88 x D 530 mm
Weight: 21.5 lbs., 9.75 kg. Shipping 23 lbs., 10.43 kg
Terminals: Output: Front panel mounted, 5 way binding posts
which are: floating, Opto-isolated from the 488 bus, guarded, remote sensed (4 wire)
and case ground. Rear panel mounted 6 pin Amphenol spec. connector
(mate supplied) with the same functions as those listed for the front panel connections.
(No additional charge).
1.6.0 General Information
Mounting: Rack mounting facilities; standard 19 ", 482.6mm and for bench use with convenient,
and removable, tilt bale, included.
Certification: A Certificate of Compliance is issued with each new instrument to certify the
calibration traceable to the National Institute of Standards and Technology (N.I.S.T.).
Warranty: Full ONE YEAR warranty on parts and labor and a full ONE YEAR warranty on
specifications and performance.

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SECTION II
2.0.0 INSTALLATION
2.1.0 Mounting
The 522 is designed for mounting in a standard 19" relay rack. When installing in the rack it is
recommended that nylon washers be placed under the mounting screws to prevent scratching
the paint.
2.2.0 Mating Connectors
All instruments are supplied with a mating AC power cord and output connector. These are:
Nomenclature EDC Part Number Quantity
1) AC Power Cord CAB008 1 ea.
2) Output Connector CON015 1 ea.
3) Connector Clamp CON013 1 ea.
2.3.0 IEEE Standard 488 Cable
A one or two meter IEEE Std. 488 cable may be obtained from EDC.
EDC Part Number CAB011 for one meter & CAB010 for two meters.
2.4.0 AC Power Input Considerations
See paragraph 3.7.0 for power line voltage changing instructions.
2.5.0 Thermal Considerations
The heat generating components are located at the rear 4 inches of the unit. Locate
the unit in the rack so that the rear 4 inches are not obstructed by other instruments,
so as to permit the free flow of air for this convection system.

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SECTION III
3.0.0 OPERATION OF THE INSTRUMENT
3.1.0 Front Panel Controls
3.1.1 Power Switch: Push-on, Push-off line power with associated indicator.
3.1.2 "Remote-Local" Switch: This switch has two positions. In the "local" position the instrument's
output is controlled by the front panel switches. In the "remote" position the instrument is
programmed by the IEEE bus, and disables all other front panel controls. This switch, when in the
"local" mode, will override the 488 bus.
3.1.3 Polarity Switch: This switch has 3 positions. "+" polarity denotes that output terminal B,
or red terminal, is positive with respect to output terminal C, or black terminal, and vice versa
for “-” polarity. The "0" position produces a "crowbar" or short circuit "0" at the output terminals.
3.1.4 Magnitude Switches: There are six. Each one controls one decade
of magnitude, and each is selectable from 0 to 10.
3.1.5 Range Switch: This is a six position switch selecting the six
ranges: 100 mA, 10 mA, 100 mV, 10 V, 100 V or option.
3.2.0 Front Panel Indicators
3.2.1 Decimal Point Indicators: The decimal point always appears in the appropriate position
depending upon which range is selected.
3.2.2 Instrument Status Enunciator
"REM" - indicates the instrument is in the remote mode with front panel controls disabled.
The output status, i.e., polarity, magnitude, and range are indicated by the LED displays and is
updated as the program is changed.
"LOC" - indicates the local or manual mode. All front panel
controls are operational and override any programmed bus commands.
"OVLD" - When illuminated, indicates an overload or possibly shorted condition in the voltage
mode. Or, an open circuit condition in the current mode.
NOTE: When the 522 senses an overload condition the unit will display "OVERLOAD" in the
digit display area. When this happens the 522 will reset itself to crowbar and output zero.
To return to the current range you must first remove the cause of the overload. Then you
must either send more data if you are in remote mode, or turn one of the switches if you are in
the local mode.

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3.2.3 Range/Function Enunciator:
"mV” indicates millivolt range/and mode
"V" indicates Volt range/and mode
"mA" indicates milliampere range/and mode
3.2.4 Decimal Indicator: A "floating" decimal point is illuminated by several LEDs and properly locates the
decimal point for the range indicated.
3.2.5 Magnitude Display Digits: Six (6) alpha-numeric displays indicate the analog value of the output.
When the unit is turned on the segments are tested and at the end of the segment test, the 488 Bus
address is displayed. In "local" the display then indicates the front panel switch settings. In "remote"
the address is displayed until a valid sequence is sent to the unit over the IEEE Bus.
3.3.0 Output Connections
3.3.1 Front Panel Connections: All terminals on the front panel are 5 way binding posts. Spacing is the
standard 3/4" centers. Connections are located as follows:
HIGH SENSE →←HIGH LOAD
LOW SENSE →←LOW LOAD
CASE GROUND →
The "load" and "sense" refers to the 4 wire remote sense capability.
NOTE: THE "LOAD-SENSE" CIRCUIT MUST BE COMPLETE IN EITHER ONE OF
TWO CONFIGURATIONS: (Please refer to Drawing #930727 in the rear of this manual for the
two-wire and four-wire connections.

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For the current mode or for driving high impedances in the voltage mode, only two wires have to be
connected to load. See Figure 2 on drawing #930727.
However, if an appreciable current is to flow in the circuit, in the voltage mode, i.e, .1 mA, then the
sense lines should be connected at the load. (See Figure 1 on Reference Drawing #930727)
This 4 wire system eliminates the IR drop and thus maintains the voltage accuracy, of the Model 522,
at the load.
3.3.2 Rear Panel Connector:
A Chassis ground
B + (high) load
C - (low) load
D No Connection
E - (low) sense
F + (high) sense
The same 4 wire sense procedures apply at the connector as discussed in 3.3.1. (SEE FIGURE 3
ON REFERENCE DRAWING 930727).
3.3.3 Chassis Ground Terminals. These connections on the front panel and at the rear connector are
connected to chassis ground.
3.4.0 Remote Programming Via The IEEE 488 Bus
3.4.1 Introduction. The EDC model 522 is compatible with the IEEE Std.488/1978. The applicable
reference publication is: IEEE Standard Digital Interface for Programmable Instrumentation (IEEE
Std. 488/1978).
Publisher: The Institute of Electrical and
Electronics Engineers, Inc.
345 East 47th Street
New York, NY 10017
The <GP-IB> makes it possible for a user to connect various instruments and components together
into a functional system. However, this system will not work without the proper software.
The operating system software offers a set of functions and commands which the user can assemble
into a written program. Once written, the user's application program, in conjunction with the
operation system software, will allow the various instruments on the <GP-IB> to generate signals,
take measurements, and allow the instrument controller to manage the resulting information.
All commands sent over the <GP-IB> must be expressed in the controller's own language such as
BASIC, FORTRAN, etc.

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There are three steps that MUST be taken when using the <GP-IB> to make the system operate.
The user MUST:
a. Understand what tasks must be performed.
b. Use the controller's language.
c. Know what kind of information the instruments are capable of exchanging.
d. READ THE CONTROLLER PROGRAMMING MANUAL THOROUGHLY!!!
3.4.1.1 The interface capabilities of the 522 are SH1, AH1, T6, L4, SR1,
RL0, PP2, DC0, DT0, E1, (see para. 3.4.4.1 for PP2 exception).
3.4.2 Setting The Instrument's Listen Address. The EDC 522 is both a "Listener and a limited Talker"
instrument. Its address is set with a "dip switch" located on the rear panel.
NOTE: THE BUS ADDRESS IS DISPLAYED UPON GOING FROM LOCAL TO REMOTE, AND
THE DISPLAYED ADDRESS IS THE DEVICE NUMBER THE MODEL 522 WILL RESPOND TO.
HOWEVER IF THE ADDRESS SWITCH IS CHANGED WHILE IN THE REMOTE MODE, THE
DISPLAY WILL NOT INDICATE THE NEW ADDRESS, ALTHOUGH THE INSTRUMENT WILL
NOW RESPOND TO THE NEW ADDRESS.
3.4.2.1 Use switches 1 through 5. They are BINARY coded.
SW1 = Bit 1
SW2 = Bit 2
SW3 = Bit 4
SW4 = Bit 8
SW5 = Bit 16
ON = True
OFF = False
Binary numbers 0 through 30 are acceptable. DO NOT SET ALL 5 SWITCHES TO "ON".
3.4.3 Interface Messages. The EDC 522 will respond to the following interface messages:
"MLA". - My Listen Address. Upon receipt of this message, the instrument will enter its listener
active state and be ready to accept a string of data bytes. ATN must be true.
"MTA". - My Talk Address. Upon receipt of this message, the instrument will enter it's Talk state
and transmit a message string as defined in Para.3.4.4.3.
"UNL". Unlisten. Upon receipt of this message, the instrument will enter its listener idle state and
will not listen to any subsequent data byte strings.
ATN must be true.