Print Load Cell Items



  • RS232 Option Board is Plug & Play field Installable
  • Suitable for point-to-point data communications
  • Selectable Modbus RTU or Custom ASCII protocols
  • Selectable baud rates to 9600
  • Isolated from meter and power grounds
  • Certified to EN 61010-1 (CE mark) and RoHS
  • Includes RJ11 connector for use with a 4 or 6-wire data cable
  • Cable assembly available for direct connection to a PC DB9
    COM port
  • Certified to EN 61010-1 (CE mark) and RoHS
DPM-3 Option T


The RS232 serial communication board allows a DPM-3 1/8 DIN digital panel meter to be interfaced to an external PC, a serial input remote display, or other device. Connection to a PC allows programming via free Windows-based Instrument Setup software, or to output readings to a PC for display and datalogging using our DPM-3-DLS datalogging software.

RS232 is normally only used for point-to-point communications via a single data line. The RS232 request-to-send line (RTS) can be set to a latched mode, where a single reading is transmitted when the line is taken high momentarily. This mode allows a single data transfer to be commanded by another device.

RS232 can drive 6-digit remote display or a Serial Input MAGNA large digit display. These units can use the received RS232 data to display readings, to switch relays for alarm or control, and to generate a scaled analog output, such as 4-20 mA or 0-10V. Two DPM-3 can be connected to a single RS232 line in multidrop fashion without loading down the RS232 driver and be digitally addressed.

If multiple meters are to be digitally addressed by a PC or PLC, use our RS485, USB, Ethernet or WiFi boards.

Two serial protocols are user-selectable for RS232: Modbus RTU and Custom ASCII. Modbus RTU is an international Master-Slave protocol which works in a Query-Response command mode, and it requires use of an external Modbus Master. The text string based Custom ASCII protocol is the simpler of the two and is recommended if the DPM-3 is the only instrument on the data line, as would normally be the case with RS232. It can be set to a command mode or a continuous data streaming mode to send serial data in the absence of an external Master. For information on our protocols, please see our DPM-3 Serial Communication Manual.


RS232 Board Specifications

Connection RX, TX, GND, RTS (optional)
Data Rates 300, 600, 1200, 2400, 4800, 9600 baud
No. of Devices on Data Line 1 (point-to-point)
Connector Single RJ11 jack
Line Length, Max 50 to 1000 ft (15 to 300 m) depending on cable and data rate
Isolation 250V rms working, 2.3 kV rms per 1 min test
ESD Protection 15 kV per IEC 1000-4-2
EMI Immunity 10 V/m per IEC 1000-4-3
EFT Protection 2 kV per IEC 1000-4-4
Short Circuit Protection Continuous
Selectable Protocols Modbus RTU, Custom ASCII.
Protocol Specifications (protocols reside on Main Board)

Modbus RTU

Standards Compliance Modbus over Serial Line Specification V1.0 (2002)
Protocol Type Master-slave, query-response command mode
Data Streaming Mode Not supported by Modbus specification
Data Formats (selectable) 1. No parity, 8 data bits, 2 stop bits
  2. Odd parity, 8 data bits, 1 stop bit
  3. Even parity, 8 data bits, 1 stop bit
Applicable Interface Boards Ethernet, USB, RS232, RS485
Conversion to Modbus TCP Automatic for Ethernet
Main Board Revision Level Level 5 or above

Custom ASCII

Standards Compliance Our proprietary protocol
Data Format No parity, 8 data bits, 1 stop bit
Protocol Type Text string based command mode or continuous data streaming mode
Data Streaming Mode User selectable for up to 60 readings/sec
Applicable Interface Boards RS232, RS485, USB
Main Board Revision Level Any
DPM-OPT-T N/A 115.00