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HC_144888093-Newcomer
3-Newcomer
May 21, 2026
Question

Kepware Server 7 and modbus ModRSsim2 simulator

  • May 21, 2026
  • 2 replies
  • 63 views

Hi there, 

I’m trying to set up a connection between Modbus TCP driver in Kepware Server 7 and modbus ModRSsim2 simulator.
Port 502 and device ID = 1 are used in both ends.
When Kepware starts, it shows the following line i log window:

   Channel1 | Starting unsolicited communication. | Protocol = 'TCP', Port = 502.
   
Should it be something like Modbus TCP Client/Master mode instead ?

In Kepware Server 7 where do you switch between Modbus TCP Client/Master mode and Modbus TCP Server/Slave/Unsolicited mode when you set up a channel ?

Any guidance would be greatly appreciated.

Thanks in advance,

Henrik
 

2 replies

H
HC_144888093-NewcomerAuthor
3-Newcomer
May 21, 2026

Issue seems to be resolved now.

I tried to have Kepware and ModRSsim on different machines and that works.

Communication is fine and Kepware is no longer using unsolicited communication:

MODBUS_TCP_CHANNEL | All channels are subscribed to a virtual network or all devices are listening to remote addresses, stopping unsolicited communication.

 

    M
    MKhatriCommunity Manager
    Support
    June 22, 2026

    Greeting  HC_14488809

     

    • The log message “Starting unsolicited communication” indicates Kepware is acting in Modbus TCP Server (Slave/Unsolicited) mode, not Client/Master.

    • In KEPServerEX v7, the mode is not a simple toggle—it depends on the driver selected while creating the channel:

      • Modbus TCP/IP Ethernet driver → works as Client/Master (polling mode) 
      • Modbus TCP/IP Unsolicited Ethernet driver → works as Server/Slave (unsolicited mode)

    • To connect to ModRSsim2 (which is a Modbus TCP Server/Slave), Kepware must be configured as Client/Master.

    • Action:

      • Delete or modify the channel using “Modbus TCP/IP Ethernet” driver (not Unsolicited)
      • Configure:
        • IP: simulator IP
        • Port: 502
        • Device ID: 1

    • After correct setup, Kepware will poll registers instead of “unsolicited communication”.

     

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