AC800M ModBus TCP communication
I'm trying to get a ModBus TCP communication up and running.
I have my CI867 port 1 setup with IP address 192.168.0.151, mask 255.255.255.0. Hardware position 3.1
I have a Siemens PLC in the other end connected to a switch.
The Siemens PLC has the IP address 192.168.0.1 and this is what I've written in under my ModBusTCP Slave in hardware position 3.1.1.
I know for sure the Siemens PLC is there because I connected the TP cable from the Siemens PLC to my Profinet network switch.
Using the webserver on the CI871 I could find the Siemens PLC and it's IP address.
Nothing happens when I connect the Siemens PLC to my ModBus switch which is connected to the CI867.
The CI867 port 1 status is OK but the ModBusTCP Slave in position 3.1.1 is showing connection down.
Trying to activate my MBTCPConnect block on channel 3 partner 1.1 gives me status -7001 connection down.
Shouldn't I at least get a good connection when I know for sure there is an equipment with the right IP address in the other end?
This is how it's setup . It's according to the post you mentioned.
Shouldn't I at least have the connection OK on port 1 regardless of what configuration the Siemens PLC has as I know for sure there is a unit with IP address 192.168.0.1 at the other end?
From your settings I can see that:
Modbus Slave Enabled = false
Are you sure your Siemens PLC is a slave?
Don't forget - after any changes, restart Connect block by switch off/on it's En parameter.
Better, if possible, restart the CPU
Do you have any activity on the line - flashing LED for Ch 1 on CI867?
1. Connection Down: Make sure the physical connection/interface between CI867 and Siemens PLC is Ok and ensure the Ping as well
2. Modbus TCP Slave: If you use Modbus TCP Slave, the slave ID will be 255. With my previous experience, Siemens PLC (don't remember the model) do check the Modbus slave ID & doesn't support the slave ID 255. So you have to use Gateway + Modbus Serial Slave concept to overcome this issue.
I would always suggest to test the modbus communication with third party simulators by both the below method to corner the issue.
* CI867 with third party Modbus Slave Simulator (To make sure the settings and programs in AC800M/CI867 is fine)
* Third Party Modbus Master Simulator with Siemens PLC (To make sure the settings and programs in Siemens PLC is fine)
Hope this might helps you.