Encoder Absolute Exemple

  • Thread starter Luciano Cardoso Vasconcelos
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Luciano Cardoso Vasconcelos

Might someone send me examples of programs using absolute encoder ?

When i learn machines before they used pulses generates for encoder as interrupts imputs in ladder program and now i would like to know how to integrate absolute encoder to do the same thing . Might anyone send me any material about this issue ?

1- On what PLC do you want to implement that?
2- I think that all kind of PLCs family include an encoder module. They are quite easy to use. First you install it on the PLC rack, then you configure it by adding in your ladder program some rungs (number of pulses per revolution, BCD or binary coded, etc.). Once it is configured, encorder position is read and can be manipulated through special registers that are accessible by ladder functions (MOV, ADD, CMP, SUB, etc.). You will get all of these info in the product manual that you have chosen.
3- If you want to directly connect the absolute encoder to the PLC and do by yourself the interface, you will need a TTL inputs module in your PLC rack. Usually you can find 8 or 16 inputs card. Why TTL?, because it as to be fast to read signals from the encoder (usual encoders are TTL compatible). Tye each encoder line to the inputs. MSB encoder line must be tight to MSB TTL input.
By using special functions in your ladder like MOV, CMP, etc. you will access all inputs at the same time (1 word = 16 bits). Remember that the PLC reads inputs once each scan time. If it is to slow to update your encoder position register, try doing that with interrupts (if your PLC has this feature). You configure the interrupt as fast as possible. When interrrupted, the PLC execute a small piece of ladder (written by you) to read these inputs and write the result in a register or memory word. Your main ladder program can then access this word that is continuously refreshed.
Good luck.