Valhalla Scientific 4300B User manual

Operation Manual
Model 4300B
Digital Micro-Ohmmeter
VALHALLA
SCIENTIFIC
Need Help? Call 800-548-9806.
www.valhallascientific.com
©2015 Valhalla Scientific, Inc. All Rights Reserved.

2
CERTIFICATION
______________________________________________________
Valhalla Scientific, Inc. certifies that this instrument was thoroughly tested and
inspected and found to meet published specifications when shipped from the
factory. Valhalla Scientific, Inc. further certifies that its calibration
measurements are traceable to the National Institute of Standards and
Technology to the extent allowed by NIST's calibration facility.
WARRANTY
______________________________________________________
The warranty period for this instrument is stated on your invoice and packing
list. Please refer to these to determine appropriate warranty dates. We will
repair or replace the instrument during the warranty period provided it is
returned to Valhalla Scientific, Inc. freight prepaid. No other warranty is
expressed or implied. We are not liable for consequential damages. Permission
and a return authorization number must be obtained directly from the factory
for warranty repairs. No liability will be accepted if returned without such
permission. Due to continuing product refinement and due to possible parts
manufacturer changes, Valhalla Scientific reserves the right to change any or all
specifications without notice.

3
TABLE OF CONTENTS
_______________________________________________________________
SECTION I UNPACKING & INSTALLATION ...................................................................................................5
1-1. INTRODUCTION............................................................................................................................................5
1-2. INITIAL INSPECTION.....................................................................................................................................5
1-3. LINE VOLTAGE/FUSE SELECTION ................................................................................................................5
1-4. INSTRUCTIONS FOR BENCH USE ..................................................................................................................6
1-5. RACK MOUNTING........................................................................................................................................6
1-6. SAFETY PRECAUTIONS ................................................................................................................................6
SECTION II SPECIFICATIONS ............................................................................................................................7
2-1. GENERAL.....................................................................................................................................................7
TABLE 2-1. Ranges and Resolutions ....................................................................................................................8
TABLE 2-2. Environmental, Power, and Physical Requirements.......................................................................8
SECTION III OPTIONAL EQUIPMENT..............................................................................................................9
3-1 AVAILABLE OPTIONS..................................................................................................................................9
3-2. TEST LEADS ..............................................................................................................................................10
SECTION IV MANUAL OPERATION................................................................................................................11
4-1. GENERAL...................................................................................................................................................11
4-2. CONNECTIONS ...........................................................................................................................................11
Figure 4-1 - Error Sources in Resistance Measurements..................................................................................12
4-3. SETTING VOLTAGE AND TEST CURRENT ...................................................................................................12
4-4. CHARGING INDUCTOR MODE ....................................................................................................................12
4-5. CABLE DISCONNECT STATUS INDICATORS ................................................................................................13
4-6. TEMPERATURE COMPENSATION ................................................................................................................14
SECTION V REMOTE OPERATION .................................................................................................................15
5-1. GENERAL...................................................................................................................................................15
5-2. THE PURPOSE OF IEEE STANDARD 488.....................................................................................................15
5-3. DEFINITIONS..............................................................................................................................................15
5-4. BUS RESTRICTIONS....................................................................................................................................16
5-5. DETAILED DESCRIPTIONS OF BUS OPERATIONS.........................................................................................16
5-6. SETTING THE IEEE ADDRESS ....................................................................................................................18
5-7. REMOTE AND LOCAL STATES ....................................................................................................................19
5-8. READING THE DISPLAY DATA ...................................................................................................................19
5-9. 4300B COMMAND SET FOR GPIB .............................................................................................................20
Table 5-2. 4300B IEEE Commands - Quick Reference........................................................................................24
SECTION VI OPTION BCD..................................................................................................................................25
6-1. GENERAL...................................................................................................................................................25
6-2. BCD PIN ASSIGNMENTS............................................................................................................................25
Table 6-1. BCD Pin Functions............................................................................................................................26
SECTION VII THEORY OF OPERATION ........................................................................................................27
7-1. GENERAL...................................................................................................................................................27
7-2. GENERAL DESCRIPTION OF CIRCUITS ........................................................................................................27
7-3. DETAILED CIRCUIT DESCRIPTIONS ............................................................................................................28
Table 7-1. A-D Converter Buffer Gains...............................................................................................................31
7-4. TROUBLESHOOTING...................................................................................................................................33

4
SECTION VIII CALIBRATION PROCEDURE.................................................................................................34
8-1. GENERAL...................................................................................................................................................34
8-2. REQUIRED TEST EQUIPMENT .....................................................................................................................34
8-3. VOLTMETER CALIBRATION .......................................................................................................................34
8-4. CURRENT SOURCE CALIBRATION ..............................................................................................................35
SECTION IX SPECIAL PROCEDURES.............................................................................................................37
9-1. GENERAL...................................................................................................................................................37
9-2. CONNECTIONS AND SETTLING TIME ..........................................................................................................37
9-3. NOISY READINGS ......................................................................................................................................37
9-4. DISCONNECTING THE CABLES ...................................................................................................................38
SECTION X MANUAL CHANGES .....................................................................................................................40
ADDENDUM 10-1: 4350ATE SPECIFICATIONS..............................................................................................41
SECTION XI PARTS LISTS .................................................................................................................................42
SECTION XII DRAWINGS AND SCHEMATICS .............................................................................................43

5
SECTION I UNPACKING & INSTALLATION
_______________________________________________________________
1-1. Introduction
The Model 4300B is a unique instrument capable of handling even the toughest resistance measurement
applications. The 4300B is designed to measure the low resistance of such items as coils, transformers,
ballasts, heater elements, etc. Some features of the 4300B that give it an edge over competitive products are:
"Charging Inductor" mode for reduced settling times.
"Disconnect Status" indicators designed with safety in mind.
Full 4-wire Kelvin terminal configuration.
Fully selectable test currents up to 10 amps.
Available locking rear Bendix connectors.
Available data outputs and remote programming capability.
Available high-speed version for assembly lines (4350ATE).
These features and more are discussed fully in the operating instructions of this manual. This device may be
dangerous if used in a manner contrary to its design! Please read this manual thoroughly before operating
your 4300B (4350ATE).
1-2. Initial Inspection
If the shipping carton is damaged, request that the carrier's agent be present when the unit is unpacked. If the
instrument appears damaged, the carrier's agent should authorize repairs before the unit is returned to the
factory. Even if the instrument appears undamaged, it may have suffered internal damage in transit that may
not be evident until the unit is operated or tested to verify conformance with its specifications. If the unit fails
to operate or fails to meet the performance specifications of Section 2, notify the carrier's agent and the nearest
Valhalla Sales Office. Retain the shipping carton for the carrier's inspection. DO NOT return equipment to
Valhalla Scientific or any of its sales offices prior to obtaining authorization to do so.
1-3. Line Voltage/Fuse Selection
The only adjustments required before placing the unit in operation are to set the rear panel switch to the
correct local AC line voltage and verify that the proper fuse for this voltage is installed as follows:
105 to 125 VAC = 3 Amp Slo-blo
210 to 250 VAC = 1 Amp Slo-blo

6
1-4. Instructions for Bench Use
The unit is supplied with all the hardware required for bench use and special instructions for use in this
manner are not necessary. However, before connecting the unit to the local power source, verify that the
power cord is equipped with a three-terminal connector (see the Safety Precautions of paragraph 1-6).
1-5. Rack Mounting
Optional brackets are available for mounting the Model 4300B (4350ATE) in a standard 19" equipment rack.
These are listed in Section 3. The size of the unit and the location of its center of gravity dictate that it must be
supported on both sides along its entire length through the use of trays or slides. If it is to be transported while
mounted in a rack, it should be supported so as to prevent upward or downward movement.
It is recommended that blank panels at least 1.75 inches high be installed between this and any other units in
the rack to ensure freedom of air flow. Under no circumstances should the ambient air temperature around the
unit exceed 50°C while the unit is in operation or 70°C when power is removed.
1-6. Safety Precautions
The power plug must be a three-contact device and should be inserted only into a three-contact mating socket
where the third contact provides a ground connection. If power is provided through an extension cable, the
ground connection must be continuous. Any discontinuity in the ground lead may render the unit unsafe
for use!
The Model 4300B (4350ATE) employs forced air cooling of the internal components. This operates
continuously and care must be taken to ensure that the intake and exhaust ports remain clear. Blocked vents
may cause a dangerous overheating condition!

7
SECTION II SPECIFICATIONS
_______________________________________________________________
2-1. General
This section contains accuracy and operational specifications for the Model 4300B. See Addendum 10-1 for
the 4350ATE High-Speed Digital Micro-ohmmeter specification changes. The accuracy specifications are
valid for a period of one year from the date of calibration at a temperature of 22°C to 28°C. Outside this
range, the temperature coefficient specification applies.
Accuracy: ±.04% of reading ±3 digits (add ±3 digits on 20mV range; ±.02% of reading on 10A range)
Temperature Coefficient: (5°C-21°C and 29°C-50°C) ±.005% of reading per °C
Temperature Sensors: "AL" and "CU" add ±.05% of reading
to accuracy specification (Temperature
compensators are accurate to ±0.1% of the rated
coefficient)
CMR Ratio: 60dB at DC, 50Hz, and 60Hz
Display: 4½ digit (19999) Liquid Crystal Display
Overload Indication: Display Flashes -1
Terminal Configuration: Four-wire Kelvin
Conversion Rate: Approximately 400 milliseconds
Maximum Kick-Back Protection: 500 Amps Peak Induced Current
Compliance Voltage (Normal Mode): 7.5 VDC nominal at 10A resistive
Compliance Voltage (Charging Inductor Mode): > 20 VDC when indicator is lit
Open Circuit Voltage (Test Current Off): < 20mV between IHI and ILO terminals

8
TABLE 2-1. Ranges and Resolutions
Full Scale VoltagesResistance
Ranges Resolutions 20mV 200mV 2V
2mΩ.0001mΩ10A --- ---
20mΩ0.001mΩ1A 10A ---
200mΩ00.01mΩ100mA 1A 10A
2Ω/2000mΩ.0001Ω/00.1mΩ10mA 100mA 1A
20Ω/20000mΩ0.001Ω/0001mΩ1mA 10mA 100mA
200Ω00.01Ω100µA 1mA 10mA
2000Ω000.1Ω--- 100µA 1mA
20000Ω0001Ω--- --- 100µA
---------------Test Current Ranges---------------
TABLE 2-2. Environmental, Power, and Physical Requirements
Environmental
Operating Temperature Range: 0 to 50°C
Humidity: 70% RH at 40°C non-condensing
Storage Temperature Range: -30°C to 70°
Power Requirements
Power Supply Voltage: 105-125 or 210-250 VAC
Power Supply Frequency: 50 - 60 Hz
Power Supply Consumption: 200VA Maximum
Physical
Dimensions: 17"(43cm)W x 17"(43cm)D x 4"(10cm)H
Weight: 9.1Kg (20 lbs) NET; 11.8Kg (26 lbs) SHIPPING

9
SECTION III OPTIONAL EQUIPMENT
3-1 Available Options
Listed below are the options available for use with the Model 4300B and 4350ATE Digital Micro-ohmmeters.
Option RX-3: Rack Ears
Option "RX-3" is a set of rack ears that permit
mounting of the instrument in a standard 19"
equipment rack.
Option TL-488: IEEE Interface
Option "TL-488" is an IEEE-488 GPIB Talk-
Listen interface that allows control via the IEEE-
488 Bus for remote range programming and
resistance measurement data acquisition. See
Section 5.
Options GP-1, GP-2: GPIB Cable
1or 2meter IEEE-488 GPIB interface cable for
use with Option TL-488.
Option BCD: Data Outputs
Option "BCD" is a parallel binary-coded-decimal
data interface with outputs for display and range
data. See Section 6.
Model 1248: Dual-Limit Comparator
The Valhalla Model 1248 may be used in
conjunction with a Model 4300B and Option BCD
above. The Model 1248 is a dual-limit
comparator that interprets the display indications
of the 4300B as either "HI", "LO" or "GO", based
on a window that is set by the user. Relay contact
closure is provided to trigger an alarm, batch
sorter, counter or other device. The mating cable
from the 4300B to the 1248 is 2½ feet in length
and designated as "IDC-3".
Option IDC-3: BCD Interface Cable
Option IDC-3 is an interface cable designed
specifically to connect the 4300B BCD output to
the inputs of the Model 1248 BCD Comparator.
It is 2½ feet in length and is terminated on one
end in a 50 pin Amphenol connector with wire
break-outs, and on the other end in a 24 pin
Amphenol connector that mates with the BCD
output port of the 4300B. See drawing number
4300-051 at the back of this manual.
Options RS232 and PAR: Interfaces
The ohmmeter is now available with optional
serial and/or printer interfaces. The serial
interface is designed to be compatible with
RS232C systems. This interface may be used for
remote data acquisition only, and does not allow
mode or range control. The printer interface is
compatible with Centronics parallel printers, and
may be configured to print raw data or labels.
If either of these options has been installed, please
refer to Section 10 for operating instructions.
Options AL and CU: Compensators
Option "AL" is a compensating temperature
sensor for aluminum (4030 ppm/
° C) providing a
20
° C or 25 ° C reference.
Option "CU" is a compensating temperature
sensor for copper (3931 ppm/
° C) providing a
20
° C or 25 ° C reference.
Option CK: Extension Cable
Option "CK" is a 4' shielded extender cable that
permits the placement of compensators in closer
proximity to the resistor under test.

10
3-2. Test Leads
Option K: General-Purpose Lead Set
Option "K" is a shielded, 4-wire Kelvin cable
set, forty-eight inches in length terminated in
"KCS" gold-plated clips.
Option KCS: Gold-Plated Clips
Option "KCS" is a light-weight, gold-plated
Kelvin clip set for 4-wire measurements on
smaller components and leads. Clips open to
1/2 inch and accommodate test currents of up
to 10 amperes.
Option KK: Heavy-Duty Cable Set
Option "KK" is a heavy-duty 4-wire Kelvin
cable set, 48-inches in length terminated in
"JAWS" clamps for connecting to large
motors, bushings, etc. Opening is 2". A
variation of this cable set is Option "KL"
which is 10 feet in length.
Option JAWS: Heavy-Duty Clamps
Option "JAWS" are the heavy-duty clamps
used to terminate Option "KK".
Option MP-1: Kelvin Micro-Probes
Option "MP-1" is a 48-inch shielded Kelvin 4-
wire cable set with a 1-ampere test current
capacity employing a set of Kelvin Micro-
Probes. The probes are equipped with
stainless steel V-1 tips separated by 0.05
inches.
Option MP-2: Kelvin Mini-Probes
Option "MP-2" is a 48-inch shielded 4-wire
cable set equipped with Kelvin Mini-Probes
having spring loaded stainless steel tips. The
V-1 tips are separated by 0.18 inches. Test
current capacity is 10 amperes.
Option MP-4/MP-5: Surface Probes
These probes permit rapid, repeatable
bonding testing on a variety of screened or
flat surfaces. Test current is evenly
distributed through the probe base while
sensing is accomplished via a spring loaded
center contact. The MP-4 target area is 1" in
diameter. The MP-5 target area is .4" in
diameter. The current capacity of both probes
is 10 amperes.
Option JB-2: Rear Bendix Connectors
Option "JB-2" is a set of rear-mounted
positive-mating locking Bendix style
connectors. The mating cable set is Option
"KC". See drawing number 4300-407 at the
back of this manual.
Option KC: Bendix Cable Set
Option "KC" is a heavy-duty 4-wire Bendix
style lead set. Option KC must be used with
Option JB-2 above.
Option BBL: Banana-to-Banana Cable
Option "BBL" is a 48" shielded cable
terminated in dual banana plugs. This cable
may be used for voltage and current
connections to the ohmmeter.
Option SL-48: Low-Thermal Leads
Option "SL-48" is a 48" shielded lead set
terminated in gold-plated spade lugs. This
lead set is designed to eliminate problems
caused by thermal EMF's and is rated for the
maximum output current of the instrument.
Option C: Banana-to-Clip Cable
Option "C" is a 48" general-purpose shielded
lead set terminated on one end in a dual
banana plug and on the other end in red and
black copper alligator clips.

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SECTION IV MANUAL OPERATION
_______________________________________________________________
4-1. General
This section of the manual contains complete instructions for manually operating the 4300B Digital Micro-
Ohmmeter.
4-2. Connections
Connections to the 4300B are made via 4 heavy-duty binding posts on the front panel. When using Valhalla
test leads, the tabbed side of each banana jack is connected to the current terminals (see below). This ensures
that current is carried in the largest conductor of the cable, and that the voltage input is shielded. A set of rear
mounted terminals is available as Option JB-2.
V
HI ☼☼IHI ←Tab
V
LO ☼☼ILO ←Tab
NOTE: If the input terminals are not connected to a load (open), the display will roll around and may or may
not indicate an overrange. This is a characteristic of the voltmeter and does not indicate a fault in the
instrument.
The four-terminal configuration of the 4300B eliminates errors normally caused by test lead and contact
resistances. In many applications the contact resistance can exceed the value of the load by several orders of
magnitude. The 4300B bypasses this potential error source by providing two terminals of constant current and
an additional two terminals for high impedance voltage measurement. The result is a fast, accurate resistance
measurement of the load, independent of the resistance of the current carrying leads.

12
Figure 4-1 - Error Sources in Resistance Measurements
Figure 4-1 illustrates how the 4-wire principle is used to eliminate lead, wire and contact resistances as
potential error sources. The internal current source inherently overcomes all series resistance (within
compliance voltage limits) and delivers a precise constant current. The internal high-impedance DVM senses
the voltage drop across the load. There is negligible contact and lead resistance error created by the voltage
measurement because the high input impedance of the DVM limits current flow in the voltage leads.
4-3. Setting Voltage and Test Current
The Full Scale Voltage is selected via three interlocking push-buttons. Three LED's directly above the push-
buttons indicate which range has been selected. The Test Current is selected via a six-position rotary switch.
Six LED's mounted to the left of the switch determine the resistance range that will be displayed as indicated
by the front panel matrix. The resistance range is found on the matrix at the intersection of the Voltage Range
and Current Range LED's.
The test current may be turned off and on via the front panel Test Current switch, by a command from the
IEEE interface board, or by a remote switch using Option "RS" as described in Section 3. An LED positioned
directly above the Test Current switch indicates the status of the current source.
4-4. Charging Inductor Mode
The Charging Inductor mode LED indicates when the standard current source compliance voltage of 7 volts is
exceeded. In this situation the 4300B provides a booster shot in excess of 20V to reduce the settling time
when a large inductive load is being measured. The display readings should be ignored when this LED is
illuminated.

13
4-5. Cable Disconnect Status Indicators
The SAFE and UNSAFE LED's indicate whether or not it is safe to disconnect the test leads from the load.
When a highly inductive load is being measured, a potentially lethal back-EMF is induced when the test
current is removed. The 4300B provides a discharge path for this back-EMF and monitors the voltage. The
SAFE LED is illuminated when the back-EMF is less than five volts.
CAUTION: Although the 4300B is protected against up to 500 Amps of inductive kickback, it is not
advisable to remove test leads with the Test Current On, or with the UNSAFE LED lit. In some
extreme applications if leads are removed or pull loose before the SAFE LED is lit, damage may occur
to the 4300B and/or injury to the operator!
The UNSAFE LED is also illuminated whenever a test current of .1A or greater is selected and the Test
Current is turned On, regardless of the load.

14
4-6. Temperature Compensation
Automatic Temperature Compensation (ATC) simulates a constant ambient temperature chamber for
materials which are normally subject to varying ambient temperatures. When the ATC mode is selected, the
temperature sensor (Options "AL" and "CU") automatically senses the ambient temperature and compensates
the reading to indicate what the actual resistance value would be in a controlled 20°C or 25°C environment.
The ATC mode is selected by pressing the Temperature Compensation On push- button. An LED positioned
directly above this push-button indicates that this mode has been selected. The temperature sensors are
connected to the 4300B via the front panel BNC connector. The temperature sensor may be extended with an
Option "CK" compensator extension cable. The FAULT indicator is illuminated when the ATC mode is
selected if the temperature sensor connections are not intact.
CAUTION: The housing of the compensator is electrically connected to the internal circuitry of the
instrument (ground), and to the VLO terminal. Care must be taken so that the housing does not contact
live circuitry.

15
SECTION V REMOTE OPERATION
_______________________________________________________________
5-1. General
This section of the manual contains instructions for operating the 4300B via the GPIB (IEEE-488) interface.
For information regarding operation using the RS232C serial or Centronics parallel interface, refer to Section
10. Throughout this section it is assumed that the reader is already familiar with manual operation of the
4300B as described in Section 4.
5-2. The Purpose of IEEE Standard 488
The purpose of the standard is to allow for interconnection of programmable instruments with a minimum of
engineering. The intent is to remove the need for adapters and the numerous types of patching cables often
encountered with other forms of interfaces. The IEEE-488 standard defines a system configuration for
programmable instruments such as calculators, voltmeters and other types of peripheral devices produced by
various manufacturers. It provides a set of rules for establishing a defined communications link with a high
degree of compatibility yet maintaining flexibility between independently manufactured products.
5-3. Definitions
Listed below are definitions of the terms used to describe the IEEE-488 interface:
Bus: A data link which is usually a set of several parallel wires within a multi-wire cable.
Bi-Directional Bus: A "highway" used for two-way communication, with input and output data being carried
on the same lines.
Bit-Parallel: A data transmission method in which all of the bits composing an item of data are present
simultaneously on a group of wires in a bus.
Byte: A group of eight data bits which is treated as a single item of data.
Byte-Serial: A data transmission method in which information, in bit-parallel bytes, is transferred
sequentially between devices.
Device Dependent Message: A message containing commands or data intended for a specific device.
Handshake: An exchange of signals between two devices which is used to control the transfer of data
between them.
Interface: The part of an instrument or system which enables it to be connected to another via a bus.
Interface Message: A message intended for interface management.
Local Operation: Operation of a device by its front panel controls (also referred to as Manual Control).
Remote Operation: Operation of device under the control of another via the bus.

16
5-4. Bus Restrictions
The IEEE-488 Interfacing Standard (also known as IEC DTC66 (WG3), ANSI MC1-1, GPIB, HP-IB, etc.),
defines a bidirectional bus for interconnecting programmable instrumentation in a bit-parallel, byte-serial
fashion. It defines limitations as follows:
1. A maximum of 15 devices may be interconnected by a single bus.
2. The total bus length may not exceed 20 meters, with a maximum interconnection length of 4 meters.
3. Maximum transmission rate is 1 megabyte per second.
4. All bus data is digital.
Of the devices on the bus, only one may be the controller which exercises control over all other devices, and is
also capable of operating as a talker or listener. The other devices may be listeners (only able to receive data)
or talkers (only able to send data), or both. The model 4300B is capable of talking and listening. The
controller may address other devices and command them to listen or talk. Only one device may talk at any
one time.
The interconnecting cable consists of sixteen signal wires and eight ground returns linking devices into a
complete system:
1. Eight data wires (DIO-0 thru DIO-7)
2. Five management wires (ATN, EOI, SRQ, IFC, and REN)
3. Three "handshake" wires (DAV, NRFD and NDAC)
Each cable connector is a plug/socket combination to permit "daisy-chaining" of units. It should be noted that
these wires use "inverse logic". That is to say that a low level indicates the true (asserted) state and a high
level indicates a false (non-asserted) state.
5-5. Detailed Descriptions of Bus Operations
The five management wires are described as follows:
ATN: Asserted by the controller whenever an address or a command is present on the bus.
EOI: May be asserted by the controller or any talker. With ATN true, EOI indicates that the controller is
polling devices. With ATN false, EOI is asserted by the talker to indicate the end of data.
SRQ: May be asserted by any device. This indicates that the device requires attention (e.g., a fault has
occurred). Normally, the controller will respond by polling to determine which device requires service.
IFC: May be asserted only by the controller. This line initializes the bus to a reset state.
REN: May be asserted only by the controller. This signal places the addressed device into the remote mode.

The three handshake wires are described as follows:
DAV: May be asserted by any talker; indicates that a valid data byte is present on the data wires.
NRFD: May be asserted by any listener. Indicates that the listener is not ready to receive data.
NDAC: May be asserted by any listener. Indicates that the listener has not yet finished reading the data byte.
The transfer of data on the bus is controlled by these three handshake wires. It is important to note that the
drivers for the handshake wires are all connected for wired-on operation. That is, as long as any of the devices
on the bus asserts a handshake line, it will remain true. There must be a complete consensus among the
devices for any handshake wire to be high (false).
The talker first waits for all devices to be ready to accept data (checks that NRFD is false) then puts one byte
of data on the bus and asserts DAV. It waits for all devices to indicate that the data has been accepted (that is,
NDAC to become false) before starting to transfer the next byte of data. This handshake protocol assures that
data on the bus is transferred at the speed of the slowest device on the bus.
Data is sent in 8-bit bytes on the DIO wires, usually (as in the 4300B) using the ISO-7 standard ASCII
characters. Table 5-1 lists each ASCII character and the bus messages applicable to each.
0 1 2 3 4 5 6 7 ←COLUMN
7 0 0 0 0 1 1 1 1
6 0 0 1 1 0 0 1 1
ISO BIT &
DIO LINE
NUMBER
5 0 1 0 1 0 1 0 1
ROW
↓
4 3 2 1 ASCII MSG ASCII MSG ASCII MSG ASCII MSG ASCII MSG ASCII MSG ASCII MSG ASCII MSG
0 0 0 0 NUL DEL SP 00 0 16 @ 00 P 16 ` p
0
0 0 0 1 SOH GTI DC 1 LLO ! 01 1 17 A 01 Q 17 a q
1
0 0 1 0 STX DC 2 “ 02 2 18 B 02 R 18 b r
2
0 0 1 1 ETX DC 3 # 03 3 19 C 03 S 19 c s
3
0 1 0 0 EOT SDC DC 4 DCI $ 04 4 20 D 04 T 20 d t
4
0 1 0 1 ENQ PCC1 NAK PPU % 05 5 21 E 05 U 21 e u
5
0 1 1 0 ACK SYN & 06 6 22 F 06 V 22 f v
6
0 1 1 1 BEL ETB ‘ 07 7 23 G 07 W 23 g w
7
1 0 0 0 BS GET CAN SPE ( 08 8 24 H 08 X 24 h x
8
1 0 0 1 HT TCT EM SPD ) 09 9 25 I 09 Y 25 i y
9
1 0 1 0 LF SUB * 10 : 26 J 10 Z 26 j z
10
1 0 1 1 VT ESC + 11 ; 27 K 11 [ 27 k {
11
1 1 0 0 FF FS , 12 < 28 L 12 \ 28 l |
12
1 1 0 1 CR GS - 13 = 29 M 13 ] 29 m }
13
1 1 1 0 SO RS . 14 > 30 N 14 ^ 30 n ~
14
1 1 1 1 SI US / 15 ? UNL O 15 _ UNT o DEL
15
ADDRESSED UNIVERSAL LISTEN TALK
COMMAND COMMAND ADDRESS ADDRESS
GROUP GROUP GROUP GROUP
(ACG) (UCG) (LAG) (TAG)
PRIMARY COMMAND
GROUP
(PCG)
SECONDARY COMMAND
GROUP
(SCG)
1 Requires Secondary Command Table 5-1 ASCII Character Codes
Notes: 1 Device Address messages shown in decimal
2 Message codes are:
DCI Device Clear LLO Local Lockout SDC Selected Device Clear
GET Device Trigger PPC Parallel Poll Configure SPD Serial Poll Disable
GTI Go to Local PPU Parallel Poll Unconfigure SPE Serial Port Enable

Note that the table is divided into two main groups; the primary command group and the secondary command
group. The secondary command group is not utilized in the 4300B.
The primary command group is further divided into four subgroups as follows:
1. Addressed Command Group - applied only to addressed devices.
2. Universal Command Group - applied to all devices.
3. Listen Address Group - set of device listen addresses.
4. Talk Address Group - set of device talk addresses.
Data in the above command groups is sent with ATN "true". These type of commands are understood by all
devices using the IEEE-488 standard. When data is sent with ATN "false", it is referred to as a device
dependent command. A device dependent command is specific to a particular device, and may or may not be
understood by other devices.
5-6. Setting the IEEE Address
The IEEE "address" is the method by which the system controller distinguishes one device on the bus from
another. The address of the 4300B is determined by the setting of a binary-weighted switch on the rear of the
instrument. An example of setting the switches to address "12" is shown below:
1 2 4 8 16
Off ║║║║║
On ÀÀ
In this case, 8+ 4= 12. In another example, the 16 + 8+ 1switches would be enabled to set the address to 25.
The address you choose is entirely dependent on your application and by the type and quantity of devices on
your IEEE bus. Some guidelines to follow are:
1) Each device on the bus must have its own unique address. Operating two devices at the same address will
produce undefined results and is not recommended.
2) Avoid setting the 4300B to address 0 (all switches off) or to address 31 (all switches on) as this may
interfere with the system controller.
3) If the setting of the switches is changed, power must be cycled in order to place the new address into
memory.
)In all future examples, the 4300B is assumed to have its address set to "12".

5-7. Remote and Local States
¾Local State
When the 4300B is in the "local" state the REMOTE indicator on the front panel is extinguished and full
manual control as described in Section 4 may be performed. The user should also note that the 4300B will
ignore commands from the GPIB while in the local state.
The 4300B automatically powers-up in the local state. Other methods for placing it in the local state are by
cycling power or by sending a return to local (RTL) command over the bus. This is done in HP Basic using
the command: LOCAL 712
To ensure compatibility with all controllers, the 4300B may also be returned to the local state by sending it the
code: L
¾Remote State
In this state the REMOTE indicator on the front panel is illuminated and all controls on the front panel are
disabled except the power switch.
The remote state may only be entered via the bus. If the 4300B receives its listen address while the REN line
is asserted, it will enter the remote state. Placing the instrument into remote is an easy way of verifying that all
connections and address selections have been done properly. This may be accomplished in HP Basic using
the command: REMOTE 712 The 4300B should enter the remote state and illuminate the REMOTE
indicator. Verify that no other device on the bus was affected by execution of this command.
5-8. Reading the Display Data
The resistance data on the 4300B's display is always available to be read by the system controller. The 4300B
does not require that a query or any other command be issued in order to retrieve it. Also, the 4300B does not
need to be in REMOTE in order for the display to be read. Retrieving the data will clear the reading buffer.
The controller must then wait until the next update of the A-to-D converter before a new value becomes
available. Data may be read at the rate of 2½ readings per second for a 4300B, or 12½ readings per second for
a 4350ATE.
The fact that the readings are always available simplifies measurement retrieval. Every time the system
controller polls the 4300B's address, an instantaneous resistance value is returned corresponding to the
displayed value.
The following program shows an example of retrieving a resistance measurement from the 4300B. The
program is written in HP Basic. If you are using a programming language or package other than HP Basic,
consult your Programmer's Manual for the correct command syntax. The 4300B is assumed to be at address
12.
10 ENTER 712;A$
20 PRINT A$
30 GOTO 10
40 END

The execution of this program results in a continuous display of the resistance measurement, updated at the
conversion rate of the instrument's A-to-D converter.
The result is returned in scientific notation, in ohms. As an example, assume that the 4300B is in the 2V and
.1mA ranges and the front panel display indicates "10567" which is 10,567 ohms. The program above is
executed.
The 4300B responds with the following number (contained in A$):
+1.0567E+4
This is the measurement in scientific notation, in ohms. The "E" signifies a power of 104, or 10000. This
means that the significant digits of the response should be multiplied by 10000.
In another example, assume that the 4300B is in the 20mV and 10A ranges, and the front panel display
indicates "1.9095" which is equal to 1.9095 milliohms. The program is executed.
The 4300B responds with the following number (contained in A$):
+1.9095E-3
This is the measurement in scientific notation, in ohms. The "E" signifies a power of 10-3, or 0.001. This
means that the significant digits of the response should be multiplied by 0.001.
)An over-range condition is indicated by:
+2.0000E±?
Each response is terminated with an "output data terminator" which is used to signal the end of the
transmission to the controller. The default terminator is a CRLF(carriage-return and line-feed). The terminator
may be changed using the "D" command. Refer to section 5-9-4.
5-9. 4300B Command Set for GPIB
This section contains a description of all commands that are recognized by the 4300B using its IEEE-488
interface (Option TL-488). As noted in section 5-8, the 4300B does not need to be queried in order to retrieve
the measured resistance data. The commands listed in this section are used to set ranges, turn the test current
on and off, and to setup internal communication protocol.
)A condensed listing of the 4300B command set is given in Table 5-2.
When sending commands to the 4300B, an "input data terminator" must be used to signal the end of the
command line. The 4300B recognizes a _ (carriage-return) or EOI asserted with the last character as valid
input terminators.
Commands must be sent using upper case characters. Multiple commands may be sent on the same line
provided that they are separated by a comma (,).