Micrologix 1400


#1

I have a Micrologix 1400 PLC using Ethernet Ip for communicating to a X-Gateway AB7632.
Can I target a specific memory location in the Gateway to write data too with a message instruction in the AB PLC? I have 2 plcs writing to the same gateway so i need to write to specific locations within the Gateway in order to not create conflict in the program.


#2

Hi,

You could use modbus TCP to able to make single writes or multi writes to the appropriate memory addresses. This will only write to those addresses. See the modbus memory maps in chapter 5 of the Ethernet User Guide.

If you are using Ethernet IP I do not think we can be sure data is not over written. You are reading and writing the entire assembly instance so there is no way to specify an offset or not read the entire thing. I would suggest trying to just change one variable and verify it does not over write the other PLC’s data.

Regards,
Deryck


#4

I cannot use Modbus TCP. That’s why I need the gateway. The Micrologix side is ethernet ip. Are you telling me there is no way to target a specific memory location in the Gateway if I use Ethernet Ip to send the information?


#5

I am checking this with my colleagues in Sweden I should have a response Monday or Tuesday.


#7

Any response yet?


#8

#9

I haven’t heard back yet I sent a direct email inquiring on the the status today. Sorry for the delay.

Deryck


#10

Hello,

Thank you for your patience with this issue.

Using the message instructions covered in the application note creates implicit message reading and writing all the data on the device and this will over write data. This is an exclusive connection similar to adding it with the EDS file. You would need to create class 3 explicit message to read individual pieces of data without over writing. Unfortunately we do not have documentation for this message instruction.

Regards,
Deryck