IET Labs PRS-370 SERIES User manual

♦PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT ♦
TEL: [phone] • [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.
PRS-370 SERIES
Programmable
Decade Resistance Substituter
(IEEE-488.2, Ethernet and USB)
Operation Manual

TEL: [phone] • [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.

♦PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT ♦
TEL: [phone] • [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.
Copyright © 2019 IET Labs, Inc.
PRS-370 IM / March. 2019
PRS-370 SERIES
Programmable
Decade Resistance Substituter
(IEEE-488.2, Ethernet and USB)
Operation Manual

TEL: [phone] • [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.
♦PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT ♦

WARRANTY
We warrant that this product is free from defects in material and workmanship and, when properly used,
will perform in accordance with applicable IET specifications. If within one year after original shipment,
it is found not to meet this standard, it will be repaired or, at the option of IET, replaced at no charge when
returned to IET. Changes in this product not approved by IET or application of voltages or currents greater
than those allowed by the specifications shall void this warranty. IET shall not be liable for any indirect,
special, or consequential damages, even if notice has been given to the possibility of such damages.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED,
INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR ANY PARTICULAR PURPOSE.

SAFETY PRECAUTIONS
The following general safety precautions must be observed during all phases of operation, service,
and repair of this instrument. Failure to comply with these precautions or with specific WARNINGS
elsewhere in this manual may impair the protection provided by the equipment. Such noncompliance
would also violate safety standards of design, manufacture, and intended use of the instrument.
IET Labs assumes no liability for the customer’s failure to comply with these precautions.
The PRS-370 complies with INSTALLATION CATEGORY I as well as POLLUTION DEGREE 2
in IEC61010-1.
If an instrument is marked CAT I (IEC Measurement Category I), or it is not marked with a
measurement category, its measurement terminals must not be connected to line-voltage mains.
The PRS-370 is an indoor use product.
DANGEROUS PROCEDURE WARNINGS
Comply with all WARNINGS - Procedures throughout in this manual and instructions on the
instrument prevent you from potential hazard. These instructions contained in the warnings must
be followed.
BEFORE APPLYING POWER
Verify that all safety precautions are taken. Make all connections to the instrument before applying
power. Note the instrument’s external markings described under “Safety Symbols”.
GROUND THE INSTRUMENT
This is a Safety Class I instrument. To minimize shock hazard, the instrument chassis and cabinet
must be connected to an electrical ground. The power terminal and the power cable must meet
International Electrotechnical Commission (IEC) safety standards.

SAFETY PRECAUTIONS CONTINUED
CAUTION
• DO NOT Operate in an Explosive Atmosphere
• Do not operate the instrument in the presence of inflammable gasses or fumes
• Operation of any electrical instrument in such an environment clearly constitutes a safety hazard
• Use Caution around live circuits and whenever hazardous voltages > 45 V are present
• Operators must not remove instrument covers
• Component replacement and internal adjustments must be made by qualified maintenance
personnel only
• DO NOT substitute parts or modify the instrument
• When working with high voltages; post warning signs, train personnel and keep unauthorized personnel
away.
Do not apply any voltage or currents to the terminals of the instrument in excess of the maximum limits
indicated in the specifications section of this manual.
To avoid the danger of introducing additional hazards, do not install substitute parts or perform unauthorized
modifications to the instrument.
Return the instrument to an IET Labs for service and repair to ensure that safety features are maintained
in operational condition.

Safety Symbols
General definitions of safety symbols used on the instrument or in manuals are listed below.
Caution symbol: the product is marked with this symbol when it is necessary for the user to
refer to the instruction manual.
Hazardous voltage symbol: the product is marked with this symbol when high voltage maybe
present on the product and an electrical shock hazard can exist.
Indicates the grounding protect terminal, which is used to prevent electric shock from the
leakage on chassis. The ground terminal must connect to earth before using the product
Direct current.
Alternating current.
Frame or chassis terminal. A connection to the frame (chassis) of the equipment which
normally includes all exposed metal structures.
On supply.
Off supply.
Hot surface. Avoid contact. Surfaces are hot and may cause personal injury if touched.
Disposal
Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/EC
This product complies with the WEEE Directive (2002/96/EC) marking requirements.
The affixed label indicates that you must not discard this electrical/ electronic product in domestic
household waste.
Product Category: With reference to the equipment types in the WEEE directive Annex 1, this product
is classified as a “Monitoring and Control instrumentation” product.
Do not dispose of electrical appliances as unsorted municipal waste, use separate collection facilities.
Contact your local government for information regarding the collection systems available. If electrical
appliances are disposed of in landfills or dumps, hazardous substances can leak into the groundwater
and get into the food chain, damaging your health and well-being.
When replacing old appliances with new one, the retailer is legally obligated to take back your old ap-
pliances for disposal.
Proposition 65 Warning for California Residents
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.
This product may contain chemicals known to the State of California to cause cancer, birth defects, or
other reproductive harm

PRS-370 Series
iiTable of Contents
CONTENTS
WARRANTY........................................................................................................... i
WARNING ............................................................................................................. ii
CAUTION .............................................................................................................. ii
CONTENTS.......................................................................................................... iii
Chapter 1: INTRODUCTION ................................................................................ 1
Chapter 2: SPECIFICATIONS .............................................................................. 3
2.1 Specifications .................................................................................................................3
2.2 General Specifications and Stability ..............................................................................4
2.2 Typical Label..................................................................................................................5
Chapter 3: OPERATION....................................................................................... 7
3.1 Initial inspection and setup ............................................................................................7
3.1.2 Purpose .................................................................................................................7
3.1.3 Storage..................................................................................................................7
3.1.4 Bench and Rack Setup..........................................................................................7
3.1.5 Front and Rear Panel ............................................................................................7
3.1.6 Power Connections...............................................................................................8
3.1.7 Environmental ......................................................................................................8
3.1.8 Safety Considerations...........................................................................................8
3.1.9 Cleaning................................................................................................................9
3.2 Connection.....................................................................................................................9
3.2.1 General Considerations ........................................................................................9
3.2.2 Electrical Considerations......................................................................................9
3.3 Condensed Operating Instructions...............................................................................10
3.4 Menu Structure.............................................................................................................10
3.4.1 Home Screen ......................................................................................................14
3.4.2 Setting a Resistance Value..................................................................................14
3.4.3 Menu Key ...........................................................................................................14
3.4.4 Resistance Settings Menu...................................................................................14
3.4.5 Standard Values Menu........................................................................................15
3.4.5.1 Set Values ..................................................................................................15
3.4.5.2 Standard Value..........................................................................................16
3.4.5.3 Decade Value............................................................................................16
3.4.5.4 Percent Value............................................................................................16
3.4.6 RTD and Other Tables Menu..............................................................................16
3.4.6.1 User Select RTD Menu .............................................................................18
3.4.7 Remote Communications Settings Menu ..........................................................18
3.4.7.1 IEEE Interface Menu.................................................................................19
3.4.7.2 Ethernet Interface Menu............................................................................19
3.4.8 About Menu........................................................................................................19
3.5 Thermal emf Considerations .................................................................................20
3.6 Environmental Conditions.....................................................................................20

PRS-370 Series
iii Table of Contents
3.7 Remote Operation..................................................................................................20
Chapter 4: PRS-DMM Mode .......................................................................... 22
4.1 PRS-DMM Mode.........................................................................................................22
4.1.1 Overview ............................................................................................................22
4.1.2 General Requirements ........................................................................................22
4.2 Configuration ...............................................................................................................23
4.2.1 Configure PRS-DMM Mode On ........................................................................23
4.2.2 Configure Accuracy............................................................................................23
4.2.1 Configure Instrument Settings............................................................................23
4.3 Performing an Adjustment ...........................................................................................24
Chapter 5: IEEE INTERFACE............................................................................. 26
5.1 Introduction..................................................................................................................26
5.2 Capabilities ..................................................................................................................26
5.3 Address Switch and Communications Settings............................................................26
5.4 GPIB Test Keyboard ....................................................................................................26
Chapter 6: MAINTENANCE .................................................................... 28
6.1 Verification of Performance .................................................................... 28
6.1.1 Calibration Interval........................................................................ 28
6.1.2 General Considerations .................................................................. 28
6.1.3 Calibration Procedure .................................................................... 28
6.1.4 Adjustment of Internal Resistors ..................................................... 28
6.1.5 Calibration Menu and Process......................................................... 30
6.1.6 Full Calibration (adjustment) .......................................................... 30
6.1.6.1 Automated versus Manual Adjustment .......................................... 31
6.1.7 Calibration History ........................................................................ 32
6.2 Replaceable Parts List ........................................................................... 33
APPENDIX A: SCPI COMMAND REFERENCE...................................... 34
APPENDIX B: IEEE.2 COMMON COMMANDS ...................................... 36

PRS-370 Series
ivTable of Contents
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INTRODUCTION
PRS-370 Series
1
Chapter 1
INTRODUCTION
The PRS-370 (Figure 1.1) is a high
precision manual and programmable decade
substituter that can leverage an 8.5 digit
DMM to improve the accuracy to < 10 ppm.
The PRS-370 is a Self-Adjusting Programmable
Resistance Standard, just connect an 8.5
digit DMM; Fluke 8508A or the Keysight
3458A to the PRS-370 via the IEEE-488
interface, and the PRS-370 becomes a short-
term stable variable standard of resistance.
The PRS-370 instructs the DMM to make a
measurement of the source resistance and then
automatically fine adjusts the output resistance
to achieve the “best” accuracy to the nominal
resistance value, typically better than 10 ppm.
The PRS-370 utilizes both the front and rear
binding posts so that the DUT and DMM
can be connected at the same time. Once the
resistance measurement is complete using
the DMM and rear binding posts, the source
resistance is switched to the front binding posts.
The PRS-370 substituter is a precision
resistance source with excellent characteristics
of stability, temperature coefficient, and power
coefficient. These features combined with
a low virtually constant “zero resistance”
make for very versatile instruments.
Operation is both local using
convenient touch screen, keypad and
standard and IEEE-488.2 interfaces.
The PRS-370 employs very low resistance,
low thermal emf relays with gold-clad silver-
alloy contacts. A special design keeps contact
resistance to a minimum. The gold plating keeps
the silver contacts from becoming tarnished
when unused, or when only low currents are
passed through them. This is most often the
case when only minute test currents are drawn
by digital multimeters and other test instruments.
Contact resistance remains low and repeatable.
High-quality gold-plated tellurium-copper
five-way binding posts serve to minimize the
thermal emf effects, which would produce
errors in dc resistance measurements.
With a resolution as low as 1 μΩand a
maximum available resistance of 20 MΩ, the
PRS-370 may be used for exacting precision
measurement applications requiring high
Figure 1.1: High Precision Programmable Decade
Resistance Substituter

INTRODUCTION
PRS-370 Series
2
accuracy, good stability, and low zero resistance.
The PRS-370 is suited for automatic and
manual calibration and testing, simulation
of RTD’s, programmable loads, and many
other laboratory and industrial applications.
The PRS Series may be rack mounted to serve as
components in measurement and control systems.
The PRS-370 (Figure 1.1) is part of the
PRS family of high precision manual and
programmable decade substituters. This
series offers a wide choice of ranges, power,
voltage, and accuracies for a wide variety
of design and production applications.
The PRS-370 uses a microcontroller design to
enhancetheeaseofuseandcalibration. Itprovides
direct resistance substitution as well as RTD
(Resistance Temperature Detector) simulation. It
allows for higher precision and tight tolerances.
The PRS-370 is a precision resistance source
with excellent characteristics of accuracy,
stability, temperature coefficient, and power
coefficient. It is direct reading without
the need to subtract “zero resistance.”
The PRS-370 offers the option of true
4-wire Kelvin measurement for calibration
applications and 2-wire mode for use
in series as a substitute resistor and for
RTD applications. The front panel display
indicates the mode selected: 2-wire or 4-wire.
There are 4 pre-programmed RTD
resistance tables, and others may be added
by the user. The controller allows for
other convenient programmed features.
The unique design makes adjustment of the
PRS-370 for calibration semiautomatic. An
internal calibration routine guides the user to
perform measurements using only a precision
ohmmeter and enter the measured values into
the PRS-370. No other standards are required.

SPECIFICATIONS
PRS-370 Series
3
Chapter 2
SPECIFICATIONS
For convenience to the user, the pertinent
specifications are given in an OPERATING
GUIDE, shown typically in Figure 2.1, affixed
to the case of the instrument.
2.1 Specifications
User interface:
Numeric keypad, softkeys and color capacitive touch
screen
Accuracy:
±(70 ppm + 1 m) 2 and 4 Terminal at 23°C ±5°C
Minimum setting: 0.100 000 
Resolution: 1  or 6 digits
Range: 0.1 - 20 M
Stability: ±50 ppm/year
Thermal emf: <15 V
Resistancedifference front to rear bindingposts:
±(2 ppm + 20 )
Maximum load: 2 A, 200 V (peak), 0.5 W whichever
applies first
Resistors: Precision wire-wound and metal foil
TC of resistors: <1 ppm/°C for 1.37 and above
Relays1: Silver alloy contacts, expected life of 108
cycles
Switching time: <10 ms second per change
RTD simulation:
9 RTD tables can be entered into memory to allow
user selection of temperature and the correct value
of resistance will automatically be programmed.
PT-100 and PT-1000 tables for both Fahrenheit and
Celsius are pre-programmed into memory locations
1 to 4.
Adjustment:
Automatic adjustment procedure utilizing a high pre-
cision DMM eliminates the requirement for manual
trimming of resistors.
Terminals:
Front and rear connections each consisting of 4
low-emf, gold-plated, tellurium-copper 5-way binding
posts are used for HI and LO terminal pairs for CUR-
RENT and SENSE. GND binding post is connected
to the case, to chassis ground.
ac Frequency Response:
Residual capacitance terminals to GND: < 850 pF
Resistance Typical ac/dc difference @ 1 kHz
0.1 -10 k<100 ppm
10 - 100 k<200 ppm
100 k- 1 M<1%
1 - 20 M<20%
Power requirements:
90 - 264 Vac , 47 - 63 Hz., 30 W. Max.
Fuse: T 0.8 A,250 V, 5 x 20 mm
Environmental conditions:
Operating: 10°C to 40°C;
<80% RH non-condensing
Storage: -40°C to 70°C; <90% RH
non-condensing
Remote Control:
GPIB:
GPIB standard 24 pin connector, conforms to IEEE-
488.2; SCPI 1994.0 command set; Hardware or
software configurable addressing range of 1 to 30.
Dimensions:
Bench model: 43 cm W x 8.9 cm H x 33 cm D
(17” x 3.5” x 13”) in front of panel: 3.8 cm (1.5”)
Rack Mount: 47 cm W x 8.9 cm H x 33 cm D
(19” x 3.5” x 13”) in front of panel: 3.8 cm (1.5”)
Weight:
Bench model: 5.5 kg (12 lb) nominal
1Note: Warranty covers relays up to expected life

SPECIFICATIONS
PRS-370 Series
4
2.2 General Specifications and Stability
Warm-up:
This unit utilizes custom designed low thermal
emf relays for high stability and low-level signal
applications. This thermal voltage is nominally
less than 15 μV under laboratory conditions.
Please note that a change in this thermal emf will
give a false drift in resistance as measured by a
dc ohmmeter, since the ohmmeter will interpret
this emf as an effective resistance. The worst
case such effective drift after warm-up is less than
±25 ppm, primarily due to stabilization of this
emf at the relay contacts as settings are changed.
Unit should be allowed to stabilize for
one hour. For maximum stability, allow
unit to warm-up over two hours.
Recommended Calibration Interval:
Typical calibration interval 12 months.
Adjustment can easily and automatically
be accomplished via calibration menu.
Adjusting the PRS-370 can improve accuracy
associated with the drift of the resistors.
Environmental:
This product complies with the
WEEE Directive (2002/96/EC)
marking requirements. The affixed
label indicates that you must not
discard this electrical/electronic
product in domestic household waste.
Product Category: With reference to the
equipment types in the WEEE Directive Annex
I, this product is classed as a “Monitoring
and Control instrumentation” product.
Effects of Humidity:
Exposure to humidity >60% for a periods of weeks
can cause the resistors to drift some of that is
reversible. It is recommended that the PRS-370 be
stored at humidities less than 50% to minimize this.
Short-term Stability:
The PRS-370 was tested for extended periods
of time. Based upon this testing the following
stability information was determined. These
specifications apply for the PRS-370 in 4
terminal mode with shorting links removed
and without switching to another value.
Typical short-term stability without
switching:
< ±(4 ppm + 100 μΩ) / 10 minutes
Typical 24 hr. Accuracy after Adjustment:
After performing an adjustment per 8.1.4
of this manual using a Fluke 8508A and
then performing a calibration verification per
8.1.3 within 24 hours the typical accuracy is:
±(30 ppm + 300 μΩ) for values <1 MΩ
±60 ppm for values > 1 MΩ
See graph below for actual performance,
shown in blue, with 6 digit resolution
across resistance range. The red lines
represent tolerance of ±(30 ppm + 300 μΩ).
Figure 2-1 Error versus Resistance up to 1 MΩ

SPECIFICATIONS
PRS-370 Series
5
FIGURE 2.1 Typical OPERATING GUIDE Affixed to Unit
(Please see label affixed to your unit)
PRS-370 PROGRAMMABLE DECADE RESISTANCE SUBSTITUTER
CONSULT INSTRUCTION MANUAL FOR PROPER INSTRUMENT OPERATION
MODEL: PRS-370 SN: B2-18431158
PRS-370 Nov. 2018
WARNING
Observe all safety rules when working with high voltages or line voltages. Connect the (GND) terminal to earth ground in order to maintain the case at a safe voltage.
Whenever hazardous voltages (>45 V) are used, take all measures to avoid accidental contact with any live components: a) Use maximum insulation and minimize the use
of bare conductors. b) Remove power when adjusting switches. c) Post warning signs and keep personnel safely away.
IET LABS, INC. www.ietlabs.com
CAGE CODE: 62015
• Long Island, New York
• Tel: [phone] • Email: [email protected]
Accuracy: ±(70ppm + 1 m) 2 and 4 Terminal at 23°C ±5°C
Minimum setting: 0.100 000 
Resolution: 1  or 6 digits
Stability: ±50 ppm/year
Range: 0.1 - 20 M
Thermal emf: <15 V
Maximum load: 2 A, 200 V (peak), 0.5 W whichever applies first
Resistors: Precision wire-wound and metal foil
RTD tables:
PT-100 and PT-1000 tables for both Fahrenheit and Celsius are programmed
into memory locations.
4 RTD tables can be entered into memory to allow user selection of temperature
and the correct value of resistance will automatically be programmed.
Adjustment:
Automatic adjustment procedure utilizing a high precision DMM eliminates the
requirement for manual trimming of resistors.
Relays1: Silver Alloy contacts, expected life of 108cycles
Terminals:
Four low-emf, gold-plated, tellurium-copper 5-way binding posts are used for HI
and LO terminal pairs for CURRENT and SENSE. GND binding post is connected
to the case, to the chassis ground and to the earth ground.
Switching time: <1 ms per change
Power requirements:
90 - 264 Vac , 47 - 63 Hz. 30 W. Max.
Remote Control:
IEEE: GPIB standard 24 pin connector, conforms to IEEE-488.2; SCPI 1994.0
command set; Software configurable addressing range of 1 to 30.
1 Note: Warranty covers relays up to expected life

SPECIFICATIONS
PRS-370 Series
6
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PRS-370 Series
OPERATION 7
Chapter 3
OPERATION
3.1 Initial inspection and setup
This instrument was tested and carefully
inspected before shipment. It should be in proper
electrical and mechanical order upon receipt.
An OPERATING GUIDE is attached to the case
of the instrument to provide ready reference to
specifications.
3.1.2 Purpose
The purpose of the PRS-370 is to source
resistance in the range of 0.1 Ωto 20 MΩfor
calibration of DMMs, meters and use as an RTD
Simulator.
3.1.3 Storage
If this instrument is to be stored for any lengthy
period of time, it should be sealed in plastic and
stored in a dry location. It should not be subjected
to temperature extremes beyond the specifica-
tions. Extended exposure to such temperatures
can result in an irreversible change in resistance,
and require recalibration.
3.1.4 Bench and Rack Setup
The PRS-370 should be placed on a stable flat
work surface. A front bail is provide to make
viewing easier.
Mount the unit in a standard 19” rack if the rack
mount option is specified.
3.1.5 Front and Rear Panel
The front panel has a capacitive touchscreen,
front binding posts, softkeys, numeric keypad
and power switch.
Front Panel
Model Ref. Description
1 Front Binding Posts
2 Capacitive Touchscreen
3 Softkeys
4 Numeric Keypad
5 Power Switch
12
34
5

OPERATION
PRS-370 Series
8
The rear panel has an IEC inlet module for con-
nection to mains power, GPIB interface and rear
binding posts.
Rear Panel
Model
Ref.
Description
1 IET Inlet Module
2 GPIB Interface
3 Rear Binding Posts
3.1.6 Power Connections
Power connection to the rear panel is through
an ac inlet module comprised of an ac connector
and fuse drawer.
Always use an power cord and outlet that has a
properly connected protection ground to avoid
shock. The PRS-370 is provided with a 3-prong
power cord with ground.
Plug the supplied IEC power cord into the instru-
ment into a power receptacle that has a ground.
The power cord may of course be selected to
match the available receptacle.
Confirm that the power supplied to the PRS-
370 meets the following requirements
Power requirements:
90 - 264 Vac , 47 - 63 Hz., 30 W. Max.
Fuse
Only replace fuse with the same type and rat-
ing.
UL/CSA type, T 0.8 A,250 V, 5 x 20 mm
3.1.7 Environmental
Do not operate the instrument in the presence
of flammable gasses or fumes.
The PRS-370 is for indoor use only.
To ensure that the safety requirements, the
specifications, and the measurement accuracy
of the PRS-370 are met, you must maintain the
environmental temperature to within the speci-
fied range by providing an appropriate cooling
clearance around the PRS-370 meter or, for the
rack-mounted type, by forcefully air-cooling
inside the rack housing if necessary.
Temperature and Humidity
Operating: 10°C to 40°C; <80% RH
non-condensing
Storage: -40°C to 70°C ; <90% RH
non-condensing
Altitude
Operating: 0 - 2000 m; storage: 0 - 4600 m
3.1.8 Safety Considerations
Refer to the Safety Summary page at the begin-
ning of this guide for general safety informa-
tion. Before installation or operation, review
this guide for safety warnings and instructions.
Safety warnings for specific procedures are
located at appropriate places throughout this
12
3

PRS-370 Series
OPERATION 9
guide.
There are no user serviceable parts inside the
PRS-370. Servicing should be referred to qual-
ified personnel.
3.1.9 Cleaning
To prevent shock unplug the 1863 and 1864 from
mains prior to cleaning.
Use a dry cloth or a cloth slightly dampened with
water to clean the external case parts.
Do not use detergents or chemical solvents.
Do not attempt to clean internally.
Denatured alcohol can be used to clean insula-
tors around binding posts.
3.2 Connection
3.2.1 General Considerations
The PRS-370 Programmable Decade Resistance
Substituter utilizes a 5-terminal connection. The
binding posts are standard laboratory type and
readily accept banana plugs, spade lugs, alligator
clips, and bare wire. Binding posts are located on
the front panel and rear panel of the instrument.
The Kelvin terminals consisting of a CURRENT
and a SENSE pair, each labeled HI and LO.
These minimize contact resistance.
4 Wire connection
The gold shorting links must be removed on the
binding posts of the PRS-370 when set to 4 Wire.
2 Wire connection
The gold shorting links must be used on the
binding posts of the PRS-370 when set to 2 Wire.
See section 3.4.4 for more information
The GND terminal on all models is connected to
the case and to earth and chassis grounds. This
may be used as a shield terminal.
3.2.2 Electrical Considerations
The performance of the PRS-370 is directly
affected by the quality of the connection to
the system under test. This is particularly true
with the precision series models having higher-
accuracy and/or lower-impedance decades.
For optimum performance, contact resistance
should be kept to a minimum by using the most
substantial mating connection possible, and by
assuring that the connection is well secured to
the binding posts.
3.3
Condensed Operating Instructions
1. Turn on the PRS-370 ON using POWER
SWITCH
2. From the Home screen, select a desired
resistance value in one of the following ways:
a) Enter a value using the number keys, then
press ENTER.
b) Press the resistance value shown on the
touch screen and then enter the resistance
value using the touch screen or keypad.
3. The source resistance will be output to the
front or rear binding posts and is indicated at on
the bottom half of the Home screen. Front and
rear binding posts can be selected by going to
Main Menu>Resistance Settings.
4. 2-Wire or 4-Wire connection mode is shown
at the top of the Home screen. This can be
changed by going to Main Menu>Resistance
Settings.