What instruction to use to read data from encoder?

I am new to plcs. I am just wondering how data is read from the encoder for controllogix AB PLCS. Also, can some explain about Bitfield distribute instruction. Rslogix help instrction didnt help me much as i still didnt get it.Also,do we use same process for both absolute and incremental encoders.One last question suppose we replace the encoder with a new one do we have to reconfigure it or is it like plug and play. Looking forward for good replies. Thanks

That depends on what plc´s or what platform you are talking about.
1746-hsc(e) for slc500, 1769-hsc for ML1500 and compactlogix, 1756-hsc for controllogix, ML1100 etc.
Please tell us what is your module and plc model.

I want to know for controllogix

That is still not nearly enough information.

How is the encoder connected to the controllogix system?

Often, absolute encoders are connected to standard DC input cards using up to 16 points and the value of all the relevant points are read at once as a decimal (binary) value. The absolute encoder will do the counting for you and simply send the number in binary using multiple wires. With controllogix, it may be required to use the CPS command to get a snapshot of the whole value while preventing the input card from changing any of the bits during the copy.

Incremental encoders are usually wired to high speed counter cards using only a few wires since they just send pulses and the card itself must do the counting.

What is the mfg/part number for the encoder?

not at work atm. But generally how do you program them.I have sick encoder. Dont have the part number atm.It had around 8 wires coming out of the encoder

I dont know how it is wired. But we use bit field distribute instruction. I went to instruction help but didn't seem to understand clearly.

via PM, bornwild is still having problems understanding the BTD instruction.

This instruction is used to copy a group of bits from one word (or group of words) to another area, while changing their locations within the group.

Suppose you wired a 12-bit absolute encoder to an input card, but the first three inputs were already taken, so you wired it to inputs 3 through 14, with point 3 being the least significant bit.

Now when the encoder is sending a binary "1", input point 3 will be on and points 4 through 14 will be off.

If you mask out the first three bits which aren't part of the data, the value you will see is 8, so how do you get it to read 1? You could bit shift three times, or do some math, (after you used MVM to block the first three bits), but the BTD can take care of both of those operations for you by only copying the group of bits you're concerned with:

Thanks a lot Paul. I got it now. Thank again mate. God Bless