Micrologix 1100 MSG help

[bfranklin]

Hey,

I have a Micrologix 1100 and I am sending 6 messages to a Yaskawa VFD, both reads and writes.
I can't figure out how to build logic to have a speed set point message write only sent to the VFD once when the set point changes from SCADA.
I can message the speed set mpoint with no issues but continuously sending the message even when it doesn't need to be sent.

Thanks

 

[dmargineau]

You will have to "insert" a buffer between the SCADA reference address and the address to be MSG "written" to the VFD then compare (NEQ) the two addresses values. When the NEQ instruction returns a true logic result then MOV the SCADA reference address value into the reference MSG "source" and enable the MSG instruction.

 

[bfranklin]

Do you have an example?

Thanks

 

[widelto]

Copy scada data into buffer 1.
Next scan compare buffer1 to scada data if the same do no thing, if different send data thru msg.

 

[bfranklin]

Thanks