Modbus MSGing Micrologix 1400

[bifftannen]

Good Day!

Would anyone be able to explain what is happening with the COP's and MOV's in this Modbus poll routine? If anything I am confused by the one COP instruction that has brackets "[" and "]" in it's source and destination. I have never seen this before. I suspect the COPs/MOV's are for bit swapping/conversion but because of this one instruction with weird syntax im confused.

Thank you very much

 

[Yacineg]

The square brackets indicate indirect addressing used for the source & destination tags. The add instructions on the branches show how the addresses are being calculated.

 

[RET]

Look like it’s swapping the high/low words, to correctly convert to floating point values on that last rung.

 

[bifftannen]

The square brackets indicate indirect addressing used for the source & destination tags. The add instructions on the branches show how the addresses are being calculated.

Thank you! Do you have a link to any documentation on indirect addressing for RSLOGIX500?

 

[bifftannen]

Look like it’s swapping the high/low words, to correctly convert to floating point values on that last rung.

Thank you much!

 

[drbitboy]

Thank you! Do you have a link to any documentation on indirect addressing for RSLOGIX500?

https://literature.rockwellautomati.../documents/rm/1766-rm001_-en-p.pdf#G8.1047332

 

[bifftannen]

https://literature.rockwellautomati.../documents/rm/1766-rm001_-en-p.pdf#G8.1047332

Thank you!