absolute encoders

[Guest mz]

Does anyone know how I can read an absolute encoder with an SLC 5/03? The HSCE module dosen't seem to support abolute encoders. Thanks.

[panic mode 246]

what kind of interface absolute encoder? did you try devicenet? or parallel?

[Snerkel 0]

I have used standard input cards with grey absolute encoders

[panic mode 246]

yep... most of them are Gray code but conversion to regular binary is very simple.

[Guest Guest]

I didn't think a std. I/O card could handle a high speed input?

[jstolaruk 9]

check out the 1746-ITV16 or 1746-ITB16 for faster inputs. There is a FAQ note here for interfacing to absolute encoders that may help.

[OkiePC 14]

I use absolute encoders with standard input cards (TTL or DC sink). The encoders I use are 12 and 14 bit binary. I do a MVM to get just the bits I need into an integer. The speed of the input card is irrelevant unless you need extremely fresh data all the time. Because the encoder itself is absolute, it will always turn on the correct bit pattern so the input card does not have to do any counting, just read the input pattern from the encoder.

[panic mode 246]

you don't need high speed inputs. standard iputs will do just fine. the higher bits will be changing slower so you won't have very precise position information during fast move but you will have it. the faster encoder spins, the more bits are going to be too fast for the plc. but that's ok. as you slow down to get to position you want, your plc will be able to see them all. if you are moving past some point at high speed, it won't matter if the plc sees 14997 or 15002. if you have application where such thing should matter, you are using wrong hardware.

[Guest Guest]

Thanks for the good info, the speed obviously does not matter, I was thinking in terms of my current relative system.