Print Load Cell Items



  • Relay Option Boards are Plug & Play field Installable
  • Choice of two relay output boards:
    Two contact relays
    Four contact relays
  • Contact relays rated 8A at 250 Vac or 24 Vdc
  • Outputs can be based on filtered or unfiltered signal input
  • Responds in one reading or after programmable delay
  • Selectable operating modes:
    Output above or below setpoint
    Latching or non-latching
    Band deviation or hysteresis around each setpoint
  • Setpoint setup via front panel pushbuttons or a PC
  • Security lockout of front panel setpoint controls
  • Certified to EN 61010-1 (CE mark) and RoHS
DPM-3 Option T
Two 8A contact relays

DPM-3 Option T
Four 8A contact relays

Electrocontact Relays

Two optional plug-in setpoint controller boards are available to add control and alarm capability to 1/8 DIN DPM-3
  • Two contact relays
  • Four contact relays
The contact relays are rated for 8A at 250 Vac or 24 Vdc and are recommended for high currents. The dual contact relays are mutually isolated Form C relays and can be wired to be normally open (NO) or normally closed (NC) when not energized. The quad contact relays are normally open (NO) Form A relays and share a common isolated ground in pairs.

Operating Modes

  • Operation above or below setpoint. Each relay may be individually programmed to be energized above or below a setpoint, or may be disabled.
  • Latching or non-latching. Each relay may be individually programmed to operate in a latching or non-latching mode. In the latching mode, when an alarm or shutdown condition is reached, the output remains in the alarm condition until it is reset by front panel pushbuttons, via the serial interface, or via the rear connector. In the non-latching mode, the output is automatically reset when the alarm condition no longer exists.
  • Band deviation mode. Each relay may be set to operate in a band deviation mode, where an alarm is generated whenever the reading is a specified number of counts above or below the setpoint. In particular, band deviation is ideal to flag an out-of-tolerance condition.
  • Hysteresis mode. Each relay may be set to operate in a hysteresis mode, where turn-on occurs at a specified amount above the setpoint and turn-off occurs at the same amount below the setpoint.
  • Filtered or unfiltered input. Relay action may be derived from either the filtered or unfiltered DPM-3 input signals. Using the unfiltered signal improves response time, which is typically 17 ms for a DPM-3 with the solid state relay board. Fast response time is one of the major strengths of the DPM-3, which can digitize analog data as often as 60 times per second. Using the filtered input reduces the chance of alarm triggering due to noise.
  • Provisions for signal noise. A programmable time delay and reduction of relay chatter can be achieved in the DPM by selecting 1 to 128 readings in binary steps (17 ms to 2.1 s) prior to updating the output. Snubber circuitry is part of the contact relay board to prolong contact life. The relay response time of counters is controlled by a selectable gate time from 10 ms to 199.99 s.

Relay Setup

Setpoint values and operating modes can be entered via front panel pushbuttons or by computer via the serial interface. Security lockout modes of the front panel pushbuttons can be set to allow operators to view and change setpoint values, view but not change setpoint values, or not view nor change setpoint values.

Electrical Connections

Form C (SPDT) dual contact relays Form C (SPDT) dual contact relays
Form C (SPDT) two contact relays
Relays can be connected to be normally
open (OC) or normally closed ($0). Relay
grounds are mutually isolated.
Form A (SPST) four contact relays
Relays are normally open (NO). Each
pair of relays shares an isolated ground.

Setpoint Operating Modes

Normal, Non-Latched Operation

Normal, non-latched relay operation for digital panel meters and counters
In this mode, the relay closes when the reading rises above the setpoint and opens when the reading falls below the setpoint. Relay ON/OFF control action is independently programmable for each of the two relays and can be reversed through a setup command.

Latched Operation

Latched relay operation for digital panel meters and counters
The relay stays actuated until reset externally. This mode can be used to shut down machinery or a process when an operating limit has been exceeded, or to maintain an alarm until acknowledged by an operator when the alarm condition has passed.

Mixed Latched and Non-Latched Operation

Mixed latched and non-latched relay operation for digital panel meters and counters
One of the relays can operate in a non-latched mode, for instance to turn off a heater when an operating temperature setpoint is reached. The other relay can operate as a latching fail-safe backup and turn off the entire process when a second, higher setpoint is reached, indicating a malfunction.

Deviation Mode Operation

Deviation mode relay operation for digital panel meters and counters
A deviation limit (50 in this example) is set up around both sides of the setpoint. The relay closes (or opens) when the reading falls within the deviation band, and opens (or closes) when the reading falls outside of this band. This mode sets up a passband around the setpoint and is often used for component testing.

Wide Hysteresis Mode Operation

Wide hysteresis mode relay operation for digital panel meters and counters
In this example, a hysteresis limit of 600 is set below the setpoint. The relay closes when the reading reaches a lower limit (the setpoint less hysteresis) and opens when the reading reaches an upper limit (the setpoint). One application is automatic tank filling. A fill operation is automatically initiated when the tank level has reached a lower level and is terminated when the level has reached an upper level.

Narrow Hysteresis Mode Operation

Narrow hysteresis mode relay operation for digital panel meters and counters
Hysteresis can be used to minimize the number of ON/OFF control cycles around a setpoint, thereby increasing the life of motors, relays, etc. A very narrow hysteresis band (such as 5 counts) can also be used to minimize relay chatter around a setpoint due to electrical noise on the signal, or due to signal feedback caused by load switching. The hysteresis limit should exceed the noise amplitude.



Power Provided by meter
Setup Front panel pushbuttons or via PC using RS232, RS485 or USB
Input Filtering Setpoint compared to either filtered or unfiltered signal.
Time Delay Unfiltered, or programmable delay from 1 to 128 readings
Relay Operating Modes 1) Activate above or below setpoint
2) Latching or non-latching
3) Hysteresis or band deviation mode around each setpoint
4) Relays disabled
Enable/Lockout Modes 1) Display and change setpoint via front panel pushbuttons.
2) Display setpoints via alarm pushbutton, but do not allow changes.
3) Disable pushbutton action for setpoints.

Alarm Status Indication

Type Two or four red LED indicators
Lamp Lit When relay is energized

Contact Relay

Form, Two Relays Form C, single-pole, double-throw (SPDT)
Form, Four Relays Form A, single-pole, single-throw (SPST), normally open (NO)
Current Rating 8A at 250 Vac or 24 Vdc
Safety Rating 250V rms working, 2.3 kV rms per 1 min test
Relay Grounds Grounds of two relays are mutually isolated
Grounds of four relays are isolated in pairs
Operate Time 7 ms (typical) from end of conversion
Release Time 5 ms (typical) from end of conversion


Operating temperature 0°C to 60°C
Storage temperature. -40°C to 85°C
Relative humidity 95% at 40°C, non-condensing
DPM-OPT-C N/A 105.00
DPM-OPT-C4 N/A 132.00