OP37 MPI address random

[PLCMania 0]

Hi, I have an OP37 panel. The panel can't communicate with the S7-300 CPU. I used the SIMATIC Manager 'Accessible Nodes', the online connected MPI nodes are always the address 2 of S7-300 CPU and a changing MPI address of OP37. That means, every time I check the 'Accessible Nodes' the displayed MPI address of OP37 is different from the last displayed address. It is random. Any idea? Thanks

[JesperMP 2]

That is very strange. If you check the application in Protool, is it set to the correct MPI parameters, in particular baudrate ? Is the cabling correct ? What are the distances, and what kind of cables and connectors are you using ? If you connect directly to the OP37 without the PLC, what happens then ? Did the panel ever work, or is it a new installation ? There is a small dipswitch next to the MPI/DP port on the OP37. It can be set to MPI/DP and RS485/RS422 respectively. Is it set to MPI/DP ?

[PLCMania 0]

Thank you Jasper, these are the answers: >>If you check the application in Protool, is it set to the correct MPI parameters, in particular baudrate ? Yes, it is set to MPI add.=1 . >>Is the cabling correct ? It is the statndard cable. >>What are the distances, and what kind of cables and connectors are you using ? They are under test and the cables are under 2m. >>If you connect directly to the OP37 without the PLC, what happens then ? I have an MPI adapter and can't connect it to OP without PLC connected. >>Did the panel ever work, or is it a new installation ? The panel has worked and was OK. >>There is a small dipswitch next to the MPI/DP port on the OP37. It can be set to MPI/DP and >>RS485/RS422 respectively. Is it set to MPI/DP ? DIP switches are set for MPI/DP connection.

[JesperMP 2]

>>If you check the application in Protool, is it set to the correct MPI parameters, in particular baudrate ? >Yes, it is set to MPI add.=1 . What about baudrate ?. I think the only baudrate that will work is 187.5K Also try to set or remove the "only master on the bus". >>Is the cabling correct ? >It is the statndard cable. >>If you connect directly to the OP37 without the PLC, what happens then ? >I have an MPI adapter and can't connect it to OP without PLC connected. I guess then that you have a cable made from one Profibus connector with PG socket + 2 m purple profibus cable + one Profibus connector. Check that the termination switches are ON in both ends.

[varlux 0]

Is your Protool integrated into STEP7? In this case, MPI net (configured in STEP7), is also avaible in Protool. So, you must control the parameters of your PLC, and you select the right MPI net. The address of your Panel is now fixed Edited 23 Nov 2006 by varlux