Grabbing data over Modbus TCP from Scadapack 350 to m340 problems

[sevun]

I've got 16-bit data at address 40200 on a Schneider Scapack 350. I can grab the data over Modbus TCP using Kepware at IP 172.16.1.100. When I try to grab the same data using READ_VAR from a Schneider m340 PRA0100, I get no data and a timeout. I'm pretty sure I'm setting the ADDM variable wrong, but not sure how.

ADDM = 'Ethernet_1{172.16.1.100}TCP.MBS'

 

[KirkC]

If you are trying to read address 40200 from the SCADAPack

NUM = 199

This is the offset from the first holding register in memory, SCADAPack counts from 1.

The SCADAPack might only answer to unitID=1, if so
ADR=ADDM('Ethernet_1{172.16.1.100}1') otherwise ADR=ADDM('Ethernet_1{172.16.1.100}')

The 4th word of the GEST array should have 20 (2*NB)
The 3rd word of the GEST array needs a timeout in 100 milliseconds

 

[drbitboy]

If you are trying to read address 40200 from the SCADAPack

NUM = 199 ...

+1


Cf. this link to see the difference between Modbus data model addressing (1-65536) and Modbus PDU addresses (0-65535).

 

[sevun]

Still no luck. I'm getting a timeout error still. Pinging the Scadapack from the m340 results in success. I'm still leaning towards the ADDM input having an issue, but I've run out of iterations to check.

 

[drbitboy]

Are you sure the device at 172.16.1.100 is running a Modbus TCP server at port 502?

What happens when you try to [telnet 172.16.1.100 502] from a CMD.EXE window? N.B. you may need to install telnet.exe first; it might be easier to work from WSL.

Is 172.16.1.100 on a VPN at another location? If yes, is it possible that the Modbus protocol (port 502, usually) is being filtered?

 

[sevun]

Using Kepware I can successfully grab the data from .100

When I telnet it goes to blank screen (doesn't say connection failed).

The two devices go through a couple of switches but no firewalls. The annoying part is I can ping it from .79 to .100 just fine.

I think I'm going to try changing directions and have the .100 device write to the .79. If I can get that working then it will have to suffice.

Thanks for everyone's help so far.

 

[drbitboy]

Did you notice the final "1" after the closing curly brace in the suggestion from @KirkC in Post #2?

Also:


https://www.plctalk.net/qanda/showthread.php?t=114114


http://www.plctalk.net/qanda/showthread.php?t=52962

 

[Lare]

Try same coding than on this threat


http://www.plctalk.net/qanda/showpost.php?p=875957&postcount=20


I assume that 'Ethernet_1' is pointing to address 0.0.3


I would try ADDM block with address '0.0.3{172.16.1.100}1' as allready mentioned.

 

[sevun]

There was another issue with modbus which was another problem. Once I got that fixed the timeouts stopped, then using the ADDM = 'Ethernet_1{172.16.1.100}1' was the trick (with 1 on end fixed it).

Orignally what I missed also was addressing:

Scapack 350, m340
30100, %IW99
40200, %MW199