EMB-2R Ethernet Modbus Gateway


EMB-2R EtherModbus; Dual Port RS-232/485/422 Modbus/TCP to serial Modbus gateway  (5-30VDC and 120 VAC power supply)

EMB-2R-I EtherModbus; Isolated RS-422/485 Dual Port Modbus/TCP to serial Modbus gateway  (5-30VDC and 120 VAC power supply)

Description of the EMB-2R

The EtherModbus gateway allows serial Modbus RTUs to communicate and interoperate with Modbus/TCP based controllers.


The Modbus standard protocol is an asynchronous protocol designed to connect directly to computer asynchronous ports. Modbus has been extended to operate over ethernet using the IP protocol suite.


This gateway converts between the Modbus TCP/IP protocol and Modbus ASCII/RTU protocols transparently. The EMB-02 enables one or more MODBUS controllers to communicate with MODBUS ASCII/RTU based serial RTUs. It will not allow Modbus/TCP RTUs to operate with a serial MODBUS controller.
The Ethernet Modbus gateway contains two independent serial ports. Each may be configured as RS-232, RS-422, or RS-485 (2 or 4 wire). When configured for RS-485 4-wire, multiple RTU polling strings may be polled on each interface.

For other applications (point-to-point direct RS-232 links or point-to-multiple-points dialed links ) see the EtherPath single port serial server. The EtherPath uses TCP/IP.

A companion product, the EtherPoll is appropriate for applications using other protocols. The EtherPoll is protocol independent, and requires no knowledge of the RTU protocol. This allows it to work with any asynchronous byte-oriented protocol with no additional configuration. The EtherPoll uses UDP/IP. It’s data sheet is here.

The EtherGate is another companion product that is protocol-aware. It enables serial SCADA devices to communicate via an ethernet network. The EtherGate is ideal for transporting SCADA protocols via ethernet. To transport SCADA protocols over Frame Relay circuits (without ethernet), use the DCB BPF Scada-FRAD.

Configuration Methods
Any web browser
Telnet Menu Interface
Direct Connection Menu Interface
SNMP agent functionality ifaces (with bus-mastering on the 4-wire)
Serial speeds from 300 bps to 230,000 bps
RJ45 10/100BaseT ethernet,ncluded
Two serial ports, DE-9 (commonly called a PC DB-9) DTE interface, individually configurable
RS-485 two or four wire interface
Set up via telnet command line interface, the serial port, or any web browser
No Dip-switches… only one reset/setup button!

Ethernet Modbus Two Port Modbus TCP to Modbus RTU and Modbus ASCII Gateway