Absolute encoder read by a siemens plc.

Hello

I am currently attending an internship in a company where they design automatic products for clients. I got an assignment to read the output of an absolute encoder by a Siemens PLC  1214C DC/DC/DC. Can someone tell me what program language is preffered or need to be used and what instruction blocks need to be used.

Also other aspects I need to keep in mind.

Thanks.

Hello Murat,

please provide more information about the encoder - what is it type, interface, etc.

Probably (i assume that yours encoder don't have any PROFINET or RS-485 interface) you will need to use High Speed Inputs of yours PLC to count impulses from encoder.

You can also find more information in this posts:

https://support.industry.siemens.com/tf/ww/en/posts/s7-1215c-to-read-20-bit-absolute-encoder-on-hsc-inputs/227207

Best regards,

Rafał

Hello Rafal

Thanks for replying.

The absolute encoder that I use is an absolute contact encoder with 128 states. The article number is: EAW0J-B24-AE0128L. This encoder is used similar to a potentiometer to make an encoded JGY-370 DC-motor position itself to a certain degree.

And the only components that I have at my disposal is the PLC and a Simatic Net CSM 1277.

Thanks.

Dear Jacek D

Thank you for your reply.

Do you know what instruction blocks to use for the conversion of gray code to decimal?

I'll await your response.

Check this threat:

https://support.industry.siemens.com/tf/ww/en/posts/gray-code-conversion/185081

But I'm afraid, that there is no TIA embeded function - You need to create yours own function.

Best regard,

Rafał

Murat2002

Dear Jacek D

Thank you for your reply.

Do you know what instruction blocks to use for the conversion of gray code to decimal?

I'll await your response.

Hello.

A helpful library with general functions that you need to get:
[Library of general functions (LGF) for SIMATIC STEP 7 (TIA Portal) and SIMATIC S7-1200 / S7-1500] 

Have a look at the 'CONVERTER OPERATIONS" section for "LGF_GreyToBinary".

~

Hello

I had a look at those files but I cannot interact. Is it because I have the version V15.1? Because only version V16 and V17 are available.

Hi,

check this:

https://support.industry.siemens.com/tf/ww/en/posts/where-can-find-the-lgf-for-tia-v15/240611

qwazze uploaded  once LGF library V15

Best regards,

Rafał

Really? You don't need any library to convert the gray code to binary, you can google a little bit.

b6 :=  g6;

b5 := b6 XOR g5;

b4 := b5 XOR g4;

b3 := b4 XOR g3;

b2 := b3 XOR g2;

b1 := b2 XOR g1;

b0 := b1 XOR g0;

Where bx are bits of binary number and gx are the bits of gray code (encoder g0 to g6 - 7 bit). The result is a binary number from 0 to 127 (unsigned). If you need a signed -64 to +63, I can sow you a next trick.

But keep in mind that optoisolated inputs are very slow, so don't expect high rotating speed from this setup.