Hello Experts,

I am facing a problem regarding Modbus Slave over TCP/IP. we need to give the data on two different ip's to another SCADA of same substaion through our SICAM PAS Gateway. All the configuration and address mapping completed as per the approved signal list.

While running Modscan the connection is established but no data is fetched through Modscan as it is showing "Exception response from the slave device" although i have tried to fetch the data with so many altered parameters also but it is giving the same response every time.

Can anyone suggest some solution to troubleshoot this problem.

Thanks in advance!

Hello,

maybe my another idea, i want know to be sure, you're talking about Modbus Slave over TCP/IP. Pls be carefuly because some other protocols are exists.

1. Modbus RTU

2. Modbus RTU over TCP/IP

3. Modbus TCP/IP

So again pls, what really protocol you want implement here?

Hello,

understand my friend, I want to be only sure what protocol he exactly use...

Update: from our experience we know that users sometimes mix names of protocols and think not correctly about them, so therefore I ask for sure to not waste time

If you are the Client you have to use modsim not mod scan.

also check the ID. I think you maynot be correctly connecting through modscan [in case you are slave] or modsim [if you are master]. 

try the following

1- check the ID number used in modscan. it should be working with 1 if it is not working with the one actually configured in net pro

2- check the connection ID's are correctly configured. check if the hex address CP is correct. also if in step7 try to use other station [with its IP address] in net pro see if it solves the issue.

3- try to communicate with fewer length in modscan say 10. maybe the starting address is not correct.

Check diagnostics CP

Auto-max

If you are the Client you have to use modsim not mod scan.

also check the ID. I think you maynot be correctly connecting through modscan [in case you are slave] or modsim [if you are master]. 

try the following

1- check the ID number used in modscan. it should be working with 1 if it is not working with the one actually configured in net pro

2- check the connection ID's are correctly configured. check if the hex address CP is correct. also if in step7 try to use other station [with its IP address] in net pro see if it solves the issue.

3- try to communicate with fewer length in modscan say 10. maybe the starting address is not correct.

Check diagnostics CP

 You are right with the third point. I had the same issue. Most probably you are defining the lengh bit too long. So just alter it to fewer length and it may work out.

thanks,

Jay

Hello guys,

no place to recommend some like 'say try 10...', basic test can be made everytime with ONE length. This is recommended.