communication between MicroLogix 1400 and Micro 850

[misly]

Hi!

Last few I've been trying to send message from MicroLogix 1400 to Micro 850. Unfortunately every time I failed . Did someone tried that before? If yes can you please send me some literature where I can see how it's done or just try to explain me.

Thanks!

 

[drbitboy]

What protocols have you tried? How much data?

I suspect there is a way to make E/IP work, but if it started getting complicated, Modbus TCP (Micro800 as Modbus TCP server) would be my solution.

 

[misly]

I tried CIP symbolic message and Modbus TCP. I suppose that I made some mistakes in setup

 

[drbitboy]

it looks like both PLCs are configured as Modbus TCP clients.

One needs to be a Modbus server, and I am pretty sure that it is only the Micro850 that can do that.

see this link:. https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DpQpaucElHeQ&ved=2ahUKEwjM58PK-6f5AhXQkIQIHT71CEsQwqsBegQIBxAF&usg=AOvVaw2_CbtcbwoS4mnfR8JmW1sO

 

[rupej]

Is the 1400 set up to use modbus? I recall needing to check some boxes in the controller setup menu.

Can't speak to the 850 but it may be similar.

 

[Saffa]

it looks like both PLCs are configured as Modbus TCP clients.

One needs to be a Modbus server, and I am pretty sure that it is only the Micro850 that can do that.

see this link:. https://www.google.com/url?sa=t&source=web&rct=j&url=https://m.youtube.com/watch%3Fv%3DpQpaucElHeQ&ved=2ahUKEwjM58PK-6f5AhXQkIQIHT71CEsQwqsBegQIBxAF&usg=AOvVaw2_CbtcbwoS4mnfR8JmW1sO

The 1400 can be both Modbus TCP server and client. Server needs configuration in the port tab to select which data files are mapped to 0x, 1x, 3x, 4x registers, and how many. For a client, reads and writes from a server is achieved using the MSG instruction.

 

[drbitboy]

The 1400 can be both Modbus TCP server and client. Server needs configuration in the port tab to select which data files are mapped to 0x, 1x, 3x, 4x registers, and how many. For a client, reads and writes from a server is achieved using the MSG instruction.

Whoops, I forgot about that tab!

Anyway, one of the PLCs needs to be the server. Say the values that need to be written to are on the 850 (N_receive), and the values where those come from are on the 1400 (N7:0). There are two ways to approach it:

1. Configure the 850 as the client and the 1400 as the server
   1. The 1400 server configuration maps its N7 data file to the 4x addresses
   2. The 850 issues a Modbus Read Multiple Holding Registers (Function code 0x03) starting at address 40001, and writes the data to its local tag N_receive.
   3. One advantage here is that the 850 immediately "knows" when the messaging fails (e.g. disconnected cable).
2. Configure the 850 as the server and the 1400 as the client
   1. The 850 server configuration maps its N_receive tag as the start of the 4x addresses
   2. The 1400 issues a Modbus Write Single Holding Register (Function code 0x06) starting at address 40001, and reads the data from N7:0.
   3. The 850 can still "know" when the messaging fails, but it would require additional heartbeat messaging, perhaps a second INT that the 1400 increments regularly.