PLC tags to modbus address?

[pav320]

Hi,

I am sure it is a newbie question, but I need help.
How do I assign a plc tag to a modbus address so that it can be pulled by a scada type system?
I am using compactlogix L53E processor with MVI69-MCM prosoft card.
I figured out how to pull data from other devices to PLC.

Please help....

 

[EddieWillers]

You'll have to define the other port of the MCM module as a Modbus Slave so that it can be polled by the SCADA system.

Print and read the User Manual, of course. Prosoft's MVI-series modules have used the same basic functionality for a decade so they're pretty well understood and documented. The configuration utility that is used with the MVI69 in particular makes it easy to view and modify the configuration.

Prosoft modules have a 5000 word database to hold all the data registers being operated on by the module. Generally you define part of that database to be Read by the PLC, and part of it to be Written by the PLC. The ladder logic then moves data between the module and the READ_DATA[x] tags and between the WRITE_DATA[x] tags and the module database in blocks.

So, you need to figure out where in the database the WRITE_DATA[x] array is being written, and then adjust the Modbus offset values for that port so that the module replies to Modbus commands from the SCADA system with the expected values.

Most general-purpose SCADA interfaces use the Modbus "Holding Registers", aka "40xxx" addresses.

If you post the configuration file from the Prosoft Utility I can have a look at it for you.