saleem patel

thumb wheel switch

2 posts in this topic

First you have to find out the thumbwheel switch output’s coding system (binary, decimal, hexadecimal). Then you have to find the output’s polarity (common anode or common cathode) in order to connect it proper to the PLC’s inputs. Each digit of the thumbwheel switch has 4 outputs. So you have to use inputs X0-X3 of the PLC for the first digit, X4-X7 for the second digit etc.

For the first digit (if the thumbwheel switch has binary outputs) you may use BIN instruction in format with Kn value to modify the input values:

LD M1000
BIN K1X0 D0

 

The instructions above will continuously convert the states of the X0-X3 inputs and store the result in D0. So D0 will contain the first digit of the thumbwheel switch (if the first digit of the switch is 1, the value in D0 will be 1 as well).
 

The situation for the other digits will be similarly.

Edited by IvanBratanov

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