My device type code is 6ED1052-1MD08-0BA0 fw ver 1.82.02, LSC 8.2.1 (2019-02-11)

My application goal is to control LOGO over Modbus-protocol and to control 4 relays mutually-exclusively (only 1 relay can be active at a time) so, that one 8-bit (or 16-bit) register would contain integer value 0...4, so that value 0=off, value 1=speed 1, value 2=speed2, value 3=speed 3 4=speed 4. Each speed (ventilation machine) corresponds to different relay (speed 1 = Q1 pulls, speed 2=Q2 pulls, etc).

Just to clarify I have already successfully implemented the mutually-exclusive control of relays so, that each relay pull can be requested by corresponding flag (M1 --> O1, M2 --> O2, M3 ->O3, M4->O4), and for each Q logic is as follows:

  Q1=M1 & !Q2 & !Q3 & !Q4,   Q2=M2 & !Q1 & !Q3 & !Q4, etc...

This part works over Mobdus-protocol control. But my question is, if I for example want one 8-bit integer value, written to device by external Modbus master with single protocol operation, to decide which Mn flag is (mutually-exclusively) set like so:

  (register value => M-bit mapping)   0=>none, 1=>M1,  2=>M2,  3=>M3,  4=>M4

...then what function blocks to use to make this integer to bit -conversion and to connect outputs to those M1..M4 flags?

Theoretically this would be possible with simple analog comparators either with range-comparator(outputs '1' if analog input in between Min and Max parameters), or with separate Min and Max comparators (to output '1' if analog input is above or below given parameter). Such simple comparator function blocks don't seem to exist and I have so far failed to identify any simple way to create this functionality using existing function blocks in Function block Diagram Editor. Any help and suggestions would be much appreciated as would be confirmation that this is not reasonably possible.

 Thank you! This worked out-of-the box and now I can control ventilation machine fan-speeds 0,1,2,3,4 remotely using single Modbus-protocol transaction to write single register with integer number corresponding to the fan speed.

ixo65

Use analog threshold trigger ...