Reading Modbus registers on slave device and validating data

Hello all,

I am relative new to PLC's.

I am looking to read 4 Modbus registers on a slave device via RS485 and then validate the data. Can a PLC be used for this?

Register 1, Asset ID
Read 'asset ID' and check against lookup table, if 'asset ID' is in the table move on.

Register 2, Location
Read 'Location' and check against lookup table, if 'Location' is in the table move on.

Register 3, Load Date/Time
Read 'Dispatch Date/Time' against current date/time and ensure 4 hours has not passed.

Register 4, Loaded Product
Read 'Loaded Product' and ensure it is equal to 'XYZ'.

If all data in the 4 registers is validated then switch control output.

Any thoughts are appreciated.

What PLC do you want to do this in?

If the said PLC has a modbus interface or modbus interface card, it's no problem reading registers from a slave.

You would read all 4 registers into the PLC first with one multiple register read command (assuming the register adresses are continuous). Then assess each register against the lookup table.

How big is the lookup table and how often would it change?

If it is large (1000+ entries) or needs to change more often than monthly, then I'd probably do this with a PC. Still read the registers with a PLC, but validate the data using the PC then signal to the PLC the end result of pass or fail

Depend on your application. I typically "validate" the data on a PC using one of the many free modbus Master simulator out there. You also need a RS485 to USB adopter for this.

+1 harryting
https://sourceforge.net/projects/advancedhmi/
USB to RS485 Converter:
https://www.automationdirect.com/adc/shopping/catalog/communications/serial/industrial_usb/usb-485m
Similar application using AdvancedHMI to Solo Process Temperature Controller via Modbus RTU.
https://accautomation.ca/advancedhmi-to-solo-process-temperature-controller/

Regards,

yes a plc can do this if it has modbus. Might be better off getting a converting or using a c-more as a convertor.