PRECISION DIGITAL PD765-6R0-00 User manual

PRECISION DIGITAL CORPORATION
89 October Hill Road • Holliston MA 01746 USA
Tel [phone] • Fax [phone]
www.predig.com
TRIDENT & TRIDENT X2
MODEL PD765
Instruction Manual
Accepts Current, Voltage, TC, & RTD Inputs
4 Digit Display, 0.56" (14 mm) or 1.20" (31 mm)
Linear or Square Root with Low-Flow Cutoff
Maximum/Minimum Display
Type 4X, NEMA 4X, IP65 Front
Universal Power Supply 85-265 VAC
12-36 VDC/12-24 VAC Power Option
Two Relays and 4-20 mA Output Option
24 VDC Transmitter Power Supply Options
USB, RS-232, & RS-485
Serial Communication Adapters Options
Free Modbus®RTU Protocol
Copy Meter Settings to Other Meters
Free MeterView®Software - Configuration & Data Acquisition

Trident Model PD765 Universal Input Meter Instruction Manual
2
Disclaimer
The information contained in this document is subject to change
without notice. Precision Digital makes no representations or war-
ranties with respect to the contents hereof, and specifically disclaims
any implied warranties of merchantability or fitness for a particular
purpose.
Registered Trademarks
MeterView®is a registered trademark of Precision Digital Corporation,
Modbus®is a registered trademark of Schneider Automation Inc. All
other trademarks mentioned in this document are the property of their
respective owners.
© 2011-2012 Precision Digital Corporation. All rights reserved.
INTRODUCTION
The Trident is a multipurpose, easy to use digital meter. It accepts
current, voltage, thermocouple, and RTD signals. The four front panel
buttons make the setup and programming an easy task.
The isolated 24 VDC transmitter power (optional) can be used to power
the input transmitter, the 4-20 mA output, or other devices.
The two relays (optional) can be used for alarm indication or process
control applications, such as pump alternation control.
Two relays and a 4-20 mA output are available together in the same
meter.
The 4-20 mA isolated output and the Modbus RTU serial communication
options make the Trident an excellent addition to any system.
Visit our Web Site
http://www.predig.com
For an Interactive VirtualMeter Demo!

Trident Model PD765 Universal Input Meter Instruction Manual
3
ORDERING INFORMATION
Trident
85-265 VAC
Model
12-36 VDC
Model Options Installed
PD765-6R0-00 PD765-7R0-00 No options
PD765-6R0-10 24 V transmitter supply
PD765-6R2-00 PD765-7R2-00 2 relays
PD765-6R2-10 2 relays & 24 V transmitter supply
PD765-6R3-00 PD765-7R3-00 4-20 mA output
PD765-6R3-10 4-20 mA output & 24 V supply
PD765-6R3-20 4-20 mA output & dual 24 V supplies
PD765-7R5-00 2 relays & 4-20 mA output
PD765-6R5-10 2 relays, 4-20 mA output, & 24 V supply
Trident X2
85-265 VAC
Model
12-36 VDC
Model Options Installed
PD765-6X0-00 PD765-7X0-00 No options
PD765-6X0-10 24 V transmitter supply
PD765-6X2-00 PD765-7X2-00 2 relays
PD765-6X2-10 2 relays & 24 V transmitter supply
PD765-6X3-00 PD765-7X3-00 4-20 mA output
PD765-6X3-10 4-20 mA output & 24 V supply
PD765-6X3-20 4-20 mA output & dual 24 V supplies
PD765-7X5-00 2 relays & 4-20 mA output
PD765-6X5-10 2 relays, 4-20 mA output, & 24 V supply
Accessories
Model Description
PDA7232 RS-232 serial adapter with PDA7420 included
PDA7420 Trident meter copy cable, 7' (2.1 m)
PDA7422 RS-422/485 serial adapter with PDA7420 included
PDA7485-I RS-232 to RS-485 isolated converter
PDA7485-N RS-232 to RS-485 non-isolated converter
PDA8485-I USB to RS-422/485 isolated converter
PDA8485-N USB to RS-422/485 non-isolated converter
PDA8006 USB Serial Adapter
MeterView®Free MeterView®software download at www.predig.com
Enclosures NEMA 4 & explosion-proof enclosures – See Web site.

Trident Model PD765 Universal Input Meter Instruction Manual
4
Table of Contents
INTRODUCTION ------------------------------------------------------------ 2
ORDERING INFORMATION --------------------------------------------- 3
SPECIFICATIONS---------------------------------------------------------- 7
General-------------------------------------------------------------------------------7
Process Input ----------------------------------------------------------------------8
Temperature Inputs -------------------------------------------------------------- 9
Relays Option-------------------------------------------------------------------- 10
Isolated 4-20 mA Transmitter Output ------------------------------------ 11
Serial Communications------------------------------------------------------- 11
COMPLIANCE INFORMATION ----------------------------------------12
Safety ------------------------------------------------------------------------------- 12
Electromagnetic Compatibility--------------------------------------------- 12
SAFETY INFORMATION ------------------------------------------------13
INSTALLATION ------------------------------------------------------------14
Unpacking------------------------------------------------------------------------- 14
Panel Mounting------------------------------------------------------------------ 14
Connections---------------------------------------------------------------------- 15
Connector Labeling ---------------------------------------------------------- 15
Power Connections ---------------------------------------------------------- 15
Signal Connections ---------------------------------------------------------- 16
Serial Communication ------------------------------------------------------- 19
Relays and 24 V Output Connections ----------------------------------- 19
Switching Inductive Loads-------------------------------------------------- 20
4-20 mA Output & Input Signal Connections -------------------------- 21
SETUP AND PROGRAMMING ----------------------------------------22
Front Panel Buttons and Status LED Indicators --------------------- 23
Display Functions and Messages----------------------------------------- 24
Main Menu ------------------------------------------------------------------------ 27
Setting Numeric Values ------------------------------------------------------ 28
Setting Up the Meter (setu) ------------------------------------------------- 29
Setting the Input Signal (inpt) -------------------------------------------- 30
Setting the Decimal Point (dc.pt) ----------------------------------------- 31
Setting the Temperature Scale (F C) ---------------------------------- 31
Setting the Relay Operation (rely) -------------------------------------- 32

Trident Model PD765 Universal Input Meter Instruction Manual
5
Relay and Alarm Operation ------------------------------------------------ 35
Pump Alternation Control Operation------------------------------------- 40
Scaling the 4-20 mA Analog Output (Aout) ---------------------------- 41
Program the Sensor Break Output Value (SEbr) --------------------- 42
Analog Output when Display is Out of Range------------------------- 42
Programming the Meter (prog)--------------------------------------------- 43
Scaling the Meter (scal)---------------------------------------------------- 44
Calibrating the Meter (Cal)------------------------------------------------- 46
Recalibrating Temperature Inputs (Cal) -------------------------------- 46
Recalibrating Process Inputs (ICal)------------------------------------- 47
Setting Up the Password (pass) ------------------------------------------- 48
Locking the Meter ------------------------------------------------------------ 48
Unlocking the Meter---------------------------------------------------------- 48
Advanced Features Menu---------------------------------------------------- 50
Advanced Features Menu & Display Messages ---------------------- 51
Offset Adjustment (Adj)----------------------------------------------------- 53
Noise Filter (fltr)------------------------------------------------------------ 53
Noise Filter Bypass (byps) ------------------------------------------------- 54
Serial Communications (serl) -------------------------------------------- 54
Protocol Selection Menu (Prot) ------------------------------------------ 54
Select Menu (SElc) ---------------------------------------------------------- 55
Linear or Square Root Function (linr or Sqrt) ---------------------- 55
Low-Flow Cutoff (cutF) ----------------------------------------------------- 56
Display Intensity (inty) ----------------------------------------------------- 56
Meter Copy Function (Copy) ----------------------------------------------- 57
Internal Calibration (ICal)-------------------------------------------------- 59
OPERATION ----------------------------------------------------------------62
Front Panel Buttons Operation -------------------------------------------- 62
Maximum/Minimum Readings---------------------------------------------- 63
MOUNTING DIMENSIONS ----------------------------------------------64
TROUBLESHOOTING----------------------------------------------------65
Diagnostics Menu (diag)----------------------------------------------------- 65
Determining Software Version -------------------------------------------- 65
Reset Meter to Factory Defaults ------------------------------------------- 66
Factory Defaults & User Settings----------------------------------------- 67
Troubleshooting Tips --------------------------------------------------------- 69
QUICK USER INTERFACE REFERENCE GUIDE----------------70

Trident Model PD765 Universal Input Meter Instruction Manual
6
Table of Figures
Figure 1. Panel Cutout and Mounting............................................... 14
Figure 2. Connector Labeling for Two Relays & 24 V Supply.........15
Figure 3. Power Connections ............................................................15
Figure 4. Transmitter Powered by Ext. Supply or Self-Powered ....16
Figure 5. Transmitters Powered by Internal Supply (Optional) ......16
Figure 6. Voltage Input Connections ................................................17
Figure 7. Thermocouple Input Connections .................................... 17
Figure 8. Three-Wire RTD Input Connections ..................................18
Figure 9. Two-Wire RTD Input Connections..................................... 18
Figure 10. Four-Wire RTD Input Connections..................................19
Figure 11. Relay & 24 V Output Connections................................... 19
Figure 12. AC and DC Loads Protection........................................... 20
Figure 13. Low Voltage DC Loads Protection ..................................20
Figure 14. 4-20 mA Output & Input Signal Powered by Meter ........ 21
Figure 15. 4-20 mA Output Powered Externally............................... 21
Figure 16. Meter Copy Connection ...................................................57
Figure 17. Meter Dimensions – Side View ........................................64
Figure 18. Case Dimensions - Top View........................................... 64

Trident Model PD765 Universal Input Meter Instruction Manual
7
SPECIFICATIONS
Except where noted all specifications apply to operation at +25°C.
General
DISPLAY Trident: 0.56" (14 mm), Trident X2: 1.20" (31 mm),
Four digits (-1999 to 9999), automatic lead zero blanking.
DISPLAY INTENSITY Eight intensity levels
DISPLAY
UPDATE RATE
Process/RTD: 3.7-5/second
Thermocouple: 1.8-2.5/second
OVERRANGE Display flashes 9999
UNDERRANGE Display flashes -1999
PROGRAMMING
METHODS
Four front panel buttons, PC and MeterView®software, or
cloning using Copy function
NOISE FILTER Programmable from 2 to 199 (0 will disable filter)
RECALIBRATION All ranges are calibrated at the factory. Recalibration is
recommended at least every 12 months.
MAX/MIN
DISPLAY
Max/min readings reached by the process are stored until
reset by the user or until power to the meter is turned off.
PASSWORD Programmable password restricts modification of
programmed settings.
NON-VOLATILE
MEMORY
All programmed settings are stored in non-volatile memory
for a minimum of ten years if power is lost.
POWER
OPTIONS
85-265 VAC, 50/60 Hz
90-265 VDC, 20 W max
or 12-36 VDC, 12-24 VAC, 6 W max
See table for power consumption
(*X: number depends on option)
Model Watts
PD765-6RX-0* 8
PD765-6RX-1, 2* 20
PD765-7RX-0* 6
FUSE Required fuse: UL Recognized, 5 A max, slow blow
Up to 6 meters may share one 5 A fuse
ISOLATED
TRANSMITTER
POWER SUPPLY
One or two transmitter power supplies (Optional)
P or P1: 24 VDC 10% @ 200 mA max. (-1 option)
P1 & P2: 24 VDC 10% @ 200 mA & 40 mA max. (-2 option)
NORMAL MODE
REJECTION
64 dB at 50/60 Hz
ISOLATION 4 kV input/output-to-power line
500 V input-to-output or output-to-P1/P2 supplies
OVERVOLTAGE
CATEGORY
Installation Overvoltage Category II:
Local level with smaller transient overvoltages than Instal-
lation Overvoltage Category III.

Trident Model PD765 Universal Input Meter Instruction Manual
8
ENVIRONMENTAL Operating temperature range: 0 to 65°C
Storage temperature range: -40 to 85°C
Relative humidity: 0 to 90% non-condensing
CONNECTIONS Removable screw terminal blocks accept 12 to 22 AWG
wire, RJ11 for serial communication adapters
ENCLOSURE 1/8 DIN, high impact plastic, UL 94V-0, color: gray
MOUNTING 1/8 DIN panel cutout required. Two panel mounting brack-
et assemblies provided
TIGHTENING
TORQUE
Screw terminal connectors: 4.5 lb-in (0.5 Nm)
OVERALL
DIMENSIONS
2.45" x 4.68" x 4.19" (62 mm x 119 mm x 106 mm)
(H x W x D)
WEIGHT 9.5 oz (269 g) (including options)
WARRANTY 3 years parts & labor
EXTENDED
WARRANTY
1 or 2 years, refer to the Price List for details.
Process Input
INPUTS Field selectable:
20 mADC (0-20, 4-20 mA) and 10 VDC (0-5, 1-5, 0-10 V)
ACCURACY ±0.05% of span ±1 count, square root: 10-100% FS
FUNCTION Linear or square root
LOW-FLOW
CUTOFF
0-9999 (0 disables cutoff function)
TEMPERATURE
DRIFT
50 PPM/C from 0 to 65C ambient
DECIMAL POINT Up to three decimal places for process inputs:
d.ddd, dd.dd, ddd.d,or dddd
CALIBRATION
RANGE
An Error message will appear if input 1 and input 2 signals
are too close together.
Input
Range
Minimum Span
Input 1 & Input 2
4-20 mA 0.40 mA
10 V 0.20 V
INPUT
IMPEDANCE
Voltage ranges: greater than 1 M
Current ranges: 50 - 100 (depending on resettable fuse impedance)
INPUT
OVERLOAD
Current input protected by resettable fuse.
Fuse resets automatically after fault is removed.

Trident Model PD765 Universal Input Meter Instruction Manual
9
Temperature Inputs
INPUTS Field selectable: type J, K, T, or E thermocouples;
100 platinum RTD (0.00385 or 0.00392 curve)
RESOLUTION 1for all thermocouples and RTD inputs
1or 0.1for Type T thermocouple
ACCURACY
Input Type Range Accuracy
Type J -58to 1382F
-50to 750C
2F
1C
Type K -58to 2300F
-50to 1260C
2F
1C
Type T -292to 700F
-180to 371C
2F
1C
Type T
0.1Res
-199.9to 700.0F
-180.0to 371.0C
1.8F
1.0C
Type E -58to 1578F
-50to 870C
2F
1C
100 RTD -328to 1382F
-200to 750C
1F
1C
COLD
JUNCTION
REFERENCE
Automatic, fixed, no user calibration needed
TEMPERATURE
DRIFT
2C maximum
0 to 65C ambient temperature
OFFSET
ADJUSTMENT
Programmable to 19.9. This parameter allows the user to
apply an offset value to the temperature being displayed.
INPUT
IMPEDANCE
Greater than 100 k
SENSOR BREAK
DETECTION
Open TC or RTD sensor indicated by display flashing oPEn.
All relays and alarm status LEDs go to alarm state.
Analog output goes to the programmed sensor break value.

Trident Model PD765 Universal Input Meter Instruction Manual
10
Relays Option
RATING 2 SPDT (Form C); rated 3 A @ 30 VDC or 3 A @ 250 VAC
resistive load; 1/14 HP @ 125/250 VAC (50 watts) for in-
ductive loads
ELECTRICAL
NOISE
SUPPRESSION
A suppressor (snubber) should be connected to each relay
contact switching inductive loads to prevent
disruption to the microprocessor’s operation.
Recommended suppressor value: 0.01 µF/470 , 250 VAC
(PDX6901).
DEADBAND 0-100% of full scale, user selectable
HIGH OR LOW
ALARM
User may program any alarm for high or low trip point.
RELAY
OPERATION
Automatic (non-latching)
Latching
Pump alternation control
RELAY RESET User selectable via front panel buttons or PC
Automatic reset only (non-latching)
Automatic + manual reset at any time (non-latching)
Manual reset only, at any time (latching)
Manual reset only after alarm condition has cleared (latching)
Automatic reset: Relays will automatically reset when the
input passes the reset point.
Manual reset: Front panel ACK button. Pressing ACK
resets all manually resettable relays.
TIME DELAY 0 to 199 seconds, on and off delays
Programmable and independent for each relay
FAIL-SAFE
OPERATION
Programmable
Independent for each relay
AUTO
INITIALIZATION
When power is applied to the meter, relays will reflect the
state of the input to the meter.
Fail-safe operation: relay coil is energized in non-alarm condition. In
case of power failure, relay will go to alarm state.

Trident Model PD765 Universal Input Meter Instruction Manual
11
Isolated 4-20 mA Transmitter Output
OUTPUT RANGE 1.00 to 23.00 mA typical
CALIBRATION Factory calibrated for 4-20 mA
SCALING RANGE 0.00 to 23.99 mA for any display range,
see output range above
ACCURACY ± 0.1% FS ± 0.004 mA
TEMPERATURE
DRIFT
0.4 uA/C from 0 to 65C ambient
Note: Analog output drift is separate from input drift.
ISOLATED
TRANSMITTER
POWER SUPPLY
One or two transmitter power supplies (Optional)
P1: 24 VDC 10% @ 200 mA max. (-1 option)
P1 & P2: 24 VDC 10% @ 200 mA & 40 mA max. (-2 option)
EXTERNAL LOOP
POWER SUPPLY
35 VDC maximum
OUTPUT LOOP
RESISTANCE Power supply Minimum Maximum
24 VDC 10 700 
35 VDC (external) 100 1200 
Serial Communications
METER
ADDRESS
PDC protocol: 0 - 99
Modbus protocol: 1 - 247
BAUD RATE 300 – 19,200 bps
TRANSMIT
TIME DELAY
Programmable between 0 and 199 ms
or transmitter always on for RS422 communication
DATA 8 bit (1 start bit, 1 stop bit)
PARITY None (1 or 2 stop bits), even, or odd
(Modbus only; PDC protocol does not use parity)
BYTE-TO-BYTE
TIMEOUT
0.01 – 2.54 sec (Modbus only)
TURN AROUND
DELAY
Less than 2 ms (fixed)
Refer to PDC and Modbus Serial Communication Protocol manuals for
details. These can be downloaded from: www.predig.com.

Trident Model PD765 Universal Input Meter Instruction Manual
12
COMPLIANCE INFORMATION
Safety
UL LISTED USA and Canada
UL 508 Industrial Control Equipment
UL FILE NUMBER E160849
FRONT PANEL UL Type 4X, NEMA 4X, IP65; panel gasket provided
LOW VOLTAGE
DIRECTIVE
EN 61010-1:2010
Safety requirements for measurement, control, and
laboratory use
Electromagnetic Compatibility
EMISSIONS EN 55011:2009 + A1:2010
Group 1 Class A ISM emissions requirements
Radiated
Emissions
Class A
AC Mains
Conducted
Emissions
Class A
IMMUNITY EN 61326-1:2006
Measurement, control, and laboratory equipment
EN 61000-6-2:2005
EMC heavy industrial generic immunity standard
RFI - Amplitude
Modulated
80 -1000 MHz 10 V/m 80% AM (1 kHz)
1.4 - 2.0 GHz 3 V/m 80% AM (1 kHz)
2.0 - 2.7 GHz 1 V/m 80% AM (1 kHz)
Electrical Fast
Transients
±2kV AC mains, ±1kV other
Electrostatic
Discharge
±4kV contact, ±8kV air
RFI - Conducted 10V, 0.15-80 MHz, 1kHz 80% AM
AC Surge ±2kV Common, ±1kV Differential
Surge 1KV (CM)
Power-Frequency
Magnetic Field
3 A/m 70%V for 0.5 period
Voltage Dips 40%V for 5 & 50 periods
70%V for 25 periods
Voltage
Interruptions
<5%V for 250 periods

Trident Model PD765 Universal Input Meter Instruction Manual
13
Note:
Testing was conducted on Trident Meters installed through the co-
vers of grounded metal enclosures with cable shields grounded at
the point of entry representing installations designed to optimize
EMC performance.
Declaration of Conformity available at www.predig.com
SAFETY INFORMATION
!
CAUTION: Read complete
instructions prior to instal-
lation and operation of the
meter.
WARNING: Risk of
electric shock.
WARNING
Hazardous voltages exist within enclosure. Installation and service
should be performed only by trained service personnel.

Trident Model PD765 Universal Input Meter Instruction Manual
14
INSTALLATION
There is no need to remove the meter from its case to com-
plete the installation, wiring, and setup of the meter.
Unpacking
Remove the meter from box. Inspect the packaging and con-
tents for damage. Report damages, if any, to the carrier.
If any part is missing or the meter malfunctions, please contact
your supplier or the factory for assistance.
Panel Mounting
Prepare a standard 1/8 DIN panel cutout – 3.622" x 1.772" (92 mm
x 45 mm). Refer to Mounting Dimensions, page 64 for more details.
Clearance: allow at least 4" (102 mm) behind the panel for wiring.
Panel thickness: 0.04" - 0.25" (1.0 mm - 6.4 mm).
Recommended minimum panel thickness to maintain Type 4X
rating: 0.06" (1.5 mm) steel panel, 0.16" (4.1 mm) plastic panel.
Remove the two mounting brackets provided with the meter (back-off
the two screws so that there is ¼" (6.4 mm) or less through the
bracket. Slide the bracket toward the front of the case and remove).
Insert meter into the panel cutout.
Install mounting brackets and tighten the screws against the panel.
To achieve a proper seal, tighten the mounting bracket screws
evenly until meter is snug to the panel along its short side. DO NOT
OVER TIGHTEN, as the rear of the panel may be damaged.
Panel
Gasket
Mounting
Bracket
Mounting
Screw
Removable
Connectors
3.622" (92mm)
1.772"
(45mm) Panel Cutout
to DIN 43700
Square Corners to 0.060"
(1.5mm) Max Radius
A
B
Tolerances:
A: +0.032 (+0.8mm)
-0.000 (-0.0mm)
B: +0.024 (+0.6mm)
-0.000 (-0.0mm)
Figure 1. Panel Cutout and Mounting

Trident Model PD765 Universal Input Meter Instruction Manual
15
Connections
All connections are made to removable screw terminal connectors
located at the rear of the meter.
!
Use copper wire with 60°C or 60/75°C insulation
for all line voltage connections. Observe all safety
regulations. Electrical wiring should be performed
in accordance with all applicable national, state,
and local codes to prevent damage to the meter
and ensure personnel safety.
Connector Labeling
The connectors label, affixed to the meter, shows the location of all
connectors available with requested configuration. It also identifies the
location of the RTD/TC selector switch.
24V OUT
EL1601
PO WER
EXC T+V+ mA+ COM
RTD
SW I TC H
TC
TC
RTD
123 456
COM NONO NC NC COM
RELA Y2 RELA Y1
4365 21
3412 5
2121
P+ P-
+-
Figure 2. Connector Labeling for Two Relays & 24 V Supply
Power Connections
Power connections are made to a two-terminal connector labeled POW-
ER on Figure 2. The meter will operate regardless of DC polarity connec-
tion. The + and - symbols are only a suggested wiring convention.
12
AC or DC
POWER
Required External Fuse:
5 A max, Slow Blow
POWER CONNECTOR
+-
Figure 3. Power Connections

Trident Model PD765 Universal Input Meter Instruction Manual
16
Signal Connections
Signal connections are made to a five-terminal connector labeled
SIGNAL on Figure 2. The COM (common) terminal is the return for all
types of input signals.
Current and Voltage Connections
The following figures show examples for current and voltage connections.
There are no switches or jumpers to set up for current and voltage inputs.
Setup and programming is performed through the front panel buttons.
COMmA+
21 354
V+ T+
EXC
External
Power
Supply
2-Wire
4-20 mA
Transmitter
-+ +-
SIGNAL CONNECTOR
COM
SIGNAL CONNECTOR
mA+
21 354
V+ T+
EXC
2-Wire 4-20 mA
Self-Powered
Transmitter
-+
Figure 4. Transmitter Powered by Ext. Supply or Self-Powered
COM
SIGNAL CONNECTOR
mA+
21 354
V+ T+
EXC
2-Wire
4-20 mA
Transmitter
-+
P+ P-
21
24V OUT
COM
SIGNAL CONNECTOR
mA+
21 354
V+ T+
EXC
3-Wire
4-20 mA
Transmitter
Signal
+
21
24V OUT
-
P+ P-
Figure 5. Transmitters Powered by Internal Supply (Optional)
The current input is protected against current overload by a resettable
fuse. The display may or may not show a fault condition depending on
the nature of the overload.
The fuse limits the current to a safe level when it detects a fault condi-
tion, and automatically resets itself when the fault condition is removed.

Trident Model PD765 Universal Input Meter Instruction Manual
17
SIGNAL CONNECTOR
21 354
Voltage
Signal
+-
COMmA+
V+ T+
EXC COM
SIGNAL CONNECTOR
mA+
21 354
V+ T+
EXC
3-Wire
Voltage
Transducer
Signal +
21
24V OUT
-
P+ P-
Figure 6. Voltage Input Connections
The meter is capable of accepting any voltage from -10 VDC to +10 VDC.
Thermocouple and RTD Connections
The following figures show examples for thermocouple and RTD con-
nections.
The RTD/TC selector switch must be set to the proper position for the
meter to accept the selected temperature input.
The input type is selected using the Setup menu.
Selected thermocouple input must correspond to thermocouple sensor
and wire type used.
SIGNAL CONNECTOR
21 354
-
+
TC
RTD TC
123 456
COMmA+
V+ T+
EXC
Switch
Position
Figure 7. Thermocouple Input Connections

Trident Model PD765 Universal Input Meter Instruction Manual
18
SIGNAL
CONNECTOR
21 354
RTD TC
123 456
COMmA+
V+ T+
EXC
Switch
Position
RTD
Sensor
Figure 8. Three-Wire RTD Input Connections
The meter accepts two, three, or four-wire RTDs. The three-wire RTD
connection has built-in lead wire compensation.
SIGNAL
CONNECTOR
21 354
RTD TC
123 456
COMmA+
V+ T+
EXC
Switch
Position
RTD
Sensor
Figure 9. Two-Wire RTD Input Connections
Lead wire compensation for two-wire RTDs can be applied using the
Adjust menu. See Offset Adjustment (Adj), page 53.

Trident Model PD765 Universal Input Meter Instruction Manual
19
SIGNAL CONNECTOR
21 354
RTD TC
123 456
COMmA+
V+ T+
EXC
Switch
Position
RTD
Sensor
NC
Figure 10. Four-Wire RTD Input Connections
The four-wire RTD connection is similar to the three-wire. One of the
leads of a four-wire RTD is not connected, and may be clipped off.
The three-wire connection provides sufficient lead wire compensation to
provide accurate readings even with long leads.
Serial Communication
Serial communication connection is made to an RJ11 connector labeled
SERIAL on Figure 2. Use PDA7232 for RS-232 interfacing.
Use PDA7422 for RS-422/485 interfacing.
Use PDA7420 for meter-to-meter interfacing for cloning purposes (i.e.
copying programmed settings from one meter to other meters).
Relays and 24 V Output Connections
Relay connections are made to a six-terminal connector labeled
RELAY1, RELAY2 on Figure 2. The COM (common) terminals of the
relays should not be confused with the COM (common) terminal of the
SIGNAL connector. The 24 VDC output is available at the connector
labeled 24V OUT, next to the relays connector.
24V OU
T
P+ P-
COM NONO NC NC COM
RELAY2 RELAY1
4365 21 21
Figure 11. Relay & 24 V Output Connections

Trident Model PD765 Universal Input Meter Instruction Manual
20
Switching Inductive Loads
The use of suppressors (snubbers) is strongly recommended when switching
inductive loads to prevent disrupting the microprocessor’s operation. The sup-
pressors also prolong the life of the relay contacts. Suppression can be obtained
with resistor-capacitor (RC) networks assembled by the user or purchased as
complete assemblies. Refer to the following circuits for RC network assembly
and installation:
C
R
C
R
Figure 12. AC and DC Loads Protection
Choose R and C as follows:
R: 0.5 to 1 for each volt across the contacts
C: 0.5 to 1 µF for each amp through closed contacts
Notes:
1. Inductive relay rating is 1/14 HP (50 W) at 115/230 VAC
2. Use capacitors rated for 250 VAC.
3. RC networks may affect load release time of solenoid loads. Check to con-
firm proper operation.
4. Install the RC network at the meter's relay screw terminals. An RC network
may also be installed across the load. Experiment for best results.
Figure 13. Low Voltage DC Loads Protection
RC Networks Available from Precision Digital
RC networks are available from Precision Digital and should be applied to each
relay contact switching an inductive load. Part number: PDX6901.
Note: Relays are de-rated to 1/14th HP (50 watts) with an inductive load.
Use a diode with a reverse
breakdown voltage two to
three times the circuit volt-
age and forward current at
least as large as the load
current.