How to Determine IP address of desktop PC(Modbus Master) connected to V130 (Modbus slave) using modbus IP

[shrikant]

Hello,

I am using V130 PLC with Ethernet card configured as Modbus IP slave to communicate with desktop PC running control software configured as Modbus IP Master. I am able to communicate, data exchange happening perfectly. Now I want to know IP address of desktop PC (Modbus master) to which PLC is currently connected, this is to limit connection with only desktop PC at a time. Are there any system operands which holds IP address of Modbus master when PLC configured as Modbus slave? 

 

[Ausman]

10 hours ago, shrikant said:

which holds IP address of Modbus master

Not that I know of, but this is such a variable that it would be hard to enforce, given the innate address changes that might occur across the network anyway, depending on the setup.  Happy for someone else to say I'm wrong.

I do recall Joe T having a method of using MAC address to verify access, but I don't know whether it can be used or is suitable for your application.....I think it was for some other sort of direct access.

I'm sure he will elaborate on this soon, given my mention of it.

cheers, Aus

[Joe Tauser]

There are no system operands which contain this data.  The MAC address method I've used returns the address of the PLC (contained in SDW 22 and 23) for router security configuration.

Maybe the Creators know if a way to sniff the incoming TCP packets using the TCP_RAW protocol.  The IP of the Master could be extracted from that.

Joe T.