1769HSC with Absolute Encoder in CompaqLogix

Hello everyone,

I'm working in a project where my client has already purchased most of the equipment, which is working on a CompaqLogix.
In some part of the project I've to read the position of an absolute encoder part number 845D-SJDZ25ANDW4, and the client purchased a High Speed Counter module to work with it 1769HSC.

Now, I've worked with absolute encoders before, but I used a regular DCInput module to read the bits in order and do some moves and converts to read the actual value.
But I've never worked with this HSC module.

I checked the manual of both (I attach the manual of the encoder, the one of the HSC can't upload because is too big, but this is the link to it http://www.google.com.mx/url?sa=t&s...7YmIDA&usg=AFQjCNHwJgBgS_QTi9S9zpjcKUje2_AcIg ), and see that the encoder uses ten pins A-K to tell position, and some others for direction, etc., but reading the 1769HSC module I see how to connect an incremental encoder and also some examples, but I haven't figured out how should I connect this absolute encoder, and how to read the position (if it can be connected). I see a A0-, B0-, Z0-, A0+, B0+, Z0+, A1- B1- Z1-, A1+ B1+ and Z1+, I don't know if I can connect the encoder to this inputs and read all the bits like a regular DCInput module.


So, I was hoping you guys could help me.

Best regards, and hope to hear from you.



Juan

Every "high speed counter" module I've seen for PLCs, including the 1769-HSC, is meant for incremental encoders.

The proper interface for an absolute encoder is either a dedicated-purpose interface on a motion controller, a fieldbus connection, or a discrete input module from whose input values the absolute encoder position value can be calculated.

The 1769-HSC is not the appropriate interface for an absolute encoder. Depending on the speed of reaction of the program a normal DC input card may be all that's needed (for a very slow operation).

At full speed what is the time between code changes (512 per revolution)? Compare that to the input time of a DC card and the scan rate of your program.

This is a natural binary encoder. That may or may not be appropriate. Check on reaction to glitches in the transitions between numbers. A Gray Code may be better.

Hello, thanks everyone for your answers,

The 1769HSC module has the following inputs:
A0+, B0+, Z0+, A0-, B0-, Z0-, A1+, B1+, Z1+, A1-, B1-, Z1-

Is it possible to plug the terminals of the absolute encoder on them, and then read and convert the bits like if it was a regular DC Input module?

I know that it would've been better to have a module for the encoder, but the client already purchased this and I want to know if I can work with it before I tell it he should've asked first and now he has to purchase a regular DC Input module instead...


Thanks and best regards

juanmdx said:

Hello, thanks everyone for your answers,

The 1769HSC module has the following inputs:
A0+, B0+, Z0+, A0-, B0-, Z0-, A1+, B1+, Z1+, A1-, B1-, Z1-

Is it possible to plug the terminals of the absolute encoder on them, and then read and convert the bits like if it was a regular DC Input module?

Thanks and best regards

Click to expand...

Simple answer.

NO

@rdrast what incremental encoder can I use for me to have a 0-360 count per revolution displayed in Ctr0currentcount using 1769-hsc?