Print Load Cell Items



  • Ethernet Communication Option Boards are Plug & Play field Installable
  • High-speed RJ45 Ethernet port for data
  • High-speed RJ11 RS485 port for setup or data
  • Can act as an Ethernet-to-RS485 gateway to an
    RS485 bus with up to 31 DPM-3 Digital panel meters
  • Allows host and remote instruments to be polled using
    Modbus commands
  • Network speeds of 10 or 100 Mbits/sec
  • RS485 speeds up to 115200 baud
  • Updated analog readings every 18 msec
  • Updated counter readings every 11 msec

DPM-3-OPT-ERS485 Ethernet and RS485 communications board


DPM-OPT-E485 communications board that plugs into the middle slot of a DPM-3 digital panel meter. It provides high-speed Ethernet and RS485 ports to connect the host instrument to an external local area network (LAN) while also serving as an Ethernet-to-RS485 gateway to an RS485 bus with with up to 31 DPM-3 digital panel meters. High data rates are a major advantage.

Ethernet operation complies with IEEE 802.3 and utilizes an industry-standard RJ45 jack for a 10/100 Base-T connection to a local area network (LAN) or directly to a PC or HMI. Multiple instruments, each with their own assigned IP address, can be individually addressed using the Modbus TCP protocol. Internet WAN connectivity is supported so that instruments can be set up and read over the Internet. Data rates can be 10 or 100 Mbits/sec depending on the router. Using Ethernet, cache of the LNET1485 board can be polled via Modbus TCP every 2 msec.

An RJ11 connector is standard for RS485 and can be used for meter programming, for data polling as a Modbus slave at up to 115200 baud, or for operation as a Modbus master at 19200 baud to an RS485 bus with up to 31 addressable DPM-3 digital panel meters. Meters on the RS485 bus can be daisy chained using our CBL03

Use of cache memory is a key feature of the DPM-3-OPT-ERS232 board. It allows the host meter to be polled at the maximum rate allowed by the meter's main board, and in turn to be polled asynchronously at a much faster rate using external Ethernet or RS485 communications with Modbus RTU/TCP commands. These are documented in our user manual . Updated analog readings can be retrieved every 17 or 20 msec, depending on the meter's 60 Hz or 50 Hz AC line noise rejection setting. Cashed counter readings can be retrieved every 10 msec.

Setup of Ethernet and RS485 communications uses our free Network Setup (LNS) utility running on a PC. That software automatically discovers the board's IP address assigned by the network router, the COM port used for RS485 communications, the meter type, and the signal conditioner type. Our CBL06 RS485-to-USB adapter cable and CBL08 RS485 splitter cable are required to connect the board's RJ11 port simultaneously to the USB port of a PC an to the external RS485 bus. The board's RS485 port can then be used to be used to set up the host instrument and instruments on the RS485 bus using our free Instrument Setup (IS) software in lieu of front panel programming.

Basic Ethernet Operation

Network with DPM-3-OPT-ERS485 to RS485 gateway board

Ethernet-to-RS485 Gateway Operation

Network with Network with DPM-3-OPT-ERS485 Ethernet to RS485 gateway board


Ethernet Operation

Ethernet standard IEEE 802.3
Ethernet connector RJ45 jack
Ethernet cable 10/100 Base-T
Data rate 10 or 100 Mbits/sec
Communications protocol Modbus TCP (same commands as Modbus RTU)
Min read interval from cache 2 msec

RS485 Operation as Slave to a PC Master

RS485 connector RJ11
RS485 cables CBL06 cable to PC USB port
Data rate 9600, 19200, 38400, 1152000 baud
Communications protocol Modbus RTU (same commands as Modbus TCP)
Min read interval from cache 5 msec
COM port Discovered by our Network Setup (NS) utility

Ethernet-to-RS485 Gateway Operation as a Master to an RS485 Bus

Connector to Ethernet RJ45
Connector to RS485 bus RJ11
Cables to meter CBL06 cable to PC USB port plus CBL08 RS485 splitter cable to RS485 bus
Cables for RS485 bus CBL03 non-reversing data cables for daisy chaining
Data rate on RS485 bus 19200 baud
Communications protocol Modbus RTU (same commands as Modbus TCP)
Time to service DPMs 17 msec or 20 msec (filtering set for 60 Hz or 50 Hz) x number of meters on RS485 bus
Time to service counters 11 msec x number of counters on RS485 bus
Provision to add transmitters BKBD breakout board

Cache Memory

Data written into cache Display value or set of 6 values (user selectable)
6 values for analog in DPM-3’s Alarm status, display value, peak, valley, display value, display value
6 values for scale meters Alarm status, display value, peak, net weight, gross weight, display value
6 values for counters Alarm status, item 1 (display value), peak, valley, item 2, item 3
Write interval for 1 value 16.666 msec or 20.000 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Write interval for 6 values 100 msec or 120 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Read inteval from cache Set by externa Modbus Master, 2 msec min for Ethernet, 10 msec min for USB

Measurement Update Intervals

Analog input meter 18 msec or 21 msec (filtering set for 60 Hz or 50 Hz noise rejection)
Totalized pulse readings Signal period or programmable gate time from 10 msec to 199.99 sec
Frequency/rate readings Gate time + 30 msec + 1-2 signal periods

Communication Protocols

Data I/O via Ethernet Modbus TCP/IP (same command set as Modbus RTU)
Meter polling via RS485 Modbus RTU
Meter programming Front panel keypad or Instrument Setup (IS) software


Board dimensions 79 x 39 mm
Mounting location Middle slot of the DPM-3 digital panel meter


Operating temperature -40°C to 85°C
Relative humidity 95% from 0°C to 85°C, non-condensing

Electrical Protection

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
DPM-OPT-E485 N/A 211.00