Interface b/w Modbus Master to Ethernet Slave PLC

Dear Rajkumar,

Please tell me your problem is now solved or not. If so, how it was solved?. We have similar problem that Modbus data update is not working between Honeywell EPLCG and Lantronix Express DR. The communication is working fine by all means, but the data update is not working. Please update me if you had come across with any solution.

Dhasleem Mohamed
We had serious trouble establishing the link between Mark VIe and Yokogawa Centum VP DCS over Lantronix, but finally managed it .

1. Upload the Latest modbus firmware from Lantronix website to the device over Lantronix device installer using straight Ethernet cable.

2. Configure the host ( in our case Enet2 port of R Controller ) as host and give its IP in the Network Adapter 1 of Toolbox ST General tab. ( You are setting the host and its IP). Our Host IP was and Lantronix IP was

3.Set the IP of the host in Lantronix setting ( Set 2 in Slave/Master settings and then assign IP of R core Enet2 port in Lantronix). A ethernet crossover cable is required between R core and Lantronix.

4. Using ModScan 32 over Rs 232 you can check if data is coming through.

5. we missed step 3 and struggled for 2-3 days.