S110 + absolute encode home position loss

Hi Adam,

I'm facing the exact same problem, but using S120 with SINA_POS in S7-1200. Every time I shut the power off the absolute encoder loss its position. How did you solve you problem?

tks

Hi!

This happens because the encoder can count just X revolutions (I don't remember the exact number). After that point if you shut down, the encoder writes seemingly a random number to the position value.

The solution for me was the abolute encoder adjustment. It can be called in starter manually, or with an acyclic communication via PLC. Every time the motor is in the same position/angle and it is in home position, I call the adjustment from the PLC, and save RAM to ROM, and I wait until it ends, and the next duty cycle starts after that.

In this case the encoder position will be 0, or of you want you can write an offset value, an the X revolution counter resets, so you can shut down the machine.

I don't know how can you configure this with a S7-1200 and S120, but these were the basic steps to do it:

1) Set p2507:Absolute encoder adjustment status =[2]
  p2507 will has [3] after position value memorized done.
2) p971:Save drive object parameters =[1] then do the RAM to ROM.
  Automaticaly change p971 =[0] after done.

If you need more help, I can search for the acyclic communication code I wrote, and I can send it to you, but I did it with Simatic Manager V5.5.

Thanks to awswer so fast...

I think my problem is related with the home positioning, because once I've created a routine(ModePos=5) using Sina_Pos block this loss os position started to happen.

But the strange thing is that when I execute the home positioning routine the absolute position goes to ZERO as I wanted to...and then I work normally...

I think this routine might not be setting p971 to 1 and the homing positioning is only in RAM...

Yes, if it is not saved into the ROM, then the position can disappear, after a shut down. I have never used the TIA blocks yet, so I can't help with this, but I am pretty sure, there must be an easy way, to save the home referece parameters to the ROM.

If I am wrong, then you have to do it "manually", and write a saving cycle.

New question published by Catalin.T is split to a separate thread with the subject S110, control the position of the table (motor) with PROFIdrive?.

Best regards
Min_Moderator

I have prepared a routine using SINA_PARA block in CPU 1214, setting these parameteres:

1 - P2599 = 0;

2 - P2507 = 2;

3 - READ P2507 should go to 3;

4 - P971 = 1 (Write to ROM);

Now it is working fine.

But I face some issues:

I have 2 axis in my application and I use only one SINA_PARA block, changing LAddr and AxisNo;

LAddr must be the same number of telegram that you are using to communicate with the PLC;

Axis number is the "Drive object number" that you can see in Starter - Configuration