Modbus RTU to Motor Drive Example

[Ziwi]

Hi Team

After sifting through all of the examples and esp some here posted by Ash Neilson and others, I have come up with something that fits my requirements. (Example based on Ash's Step Logic)

I have had it working for a week now, and ironed out most of the bugs. It is not the most elegant bit of code, but maybe of use to some new players.

Basically I have 3 SEW LTP motor drives. I am interested in 17 registers - non contiguous. Randomly from 0 -181. So I devised a datatable with Slave ID, Register #, Read Value, Write Value and if the register is writeable. A pointer increments after each read/write operation and then loads up the next values for the next operation. if writeable it write's, if not it reads, and it keeps looping.

I did have intentions of assigning a priority system - but haven't figured this out. Also in hindsight should have possibly kept the read and write blocks separate.

Feedback welcomed, hopefully with some more input we could put together a real useful template/example for comms with non Uni devices.

Attached is the example, you are most interested in the "Modbus Step Logic" subroutine and the Modbus datatable. The relevant operands are MI300-MI399

I used the datatables in conjunction with excel to edit operand descriptions, and then imported them back into visilogic. (Can't upload excel files?)

Modbus_Template.vlp