We have an machine with Sinumerik 840D and linear motors installed. We need to replace a linear scale for Z axis (reading head was broken). Originally there was LC 481 head installed. Now LC 481 is not producing more by Heidenhain, and there is the replacement - a scale with LC 4x3 head. After we have this head connected to CNC and after initialization procedure (MD1017=-1), we have an alarm 26020 - Axis %1 encoder %2 hardware fault %3 during encoder initialization. There is a code 2080H which means:

Bit 7: Control check error, Note: SW 4.2 and higher, synchronous linear motor

Bit 13: CRC error

We have an PWM20 device from Heidenhain so we have tested this head with ATS software, and it works perfectly - we can get incremental position, absolute position data and so on, and there is no any errors like CRC so it seems that reading head is working normally. Maybe somebody had the same problem and could give us an advice?

Thanks all.

Hi,

was there any solutions for the error ?

We have also this message.

It's a very old topic but it will remain for long...

LC481 from Heidenhain used a so call Endat 1.x (or Endat 2.1)... the name is not that important.

This type sent the absolute position of the encoder BUT ALSO the incremental signals A,/A,B,/B,etc.

Most new models from Heidenhain are based on Endat 2.2 and the encoder sends ONLY the absolute position, NO incremental value. Off course they sell also a backward compatible model, with absolute and also incremental values but you must ask for it. If you ignore the small problem of backward compatibility you will get a brand new, perfect and unusable encoder head.

Sinumerik 840D Powerline (with Simodrive 611D) does not have an interface for Endat 2.2 and needs the incremental signals: It reads the absolute position on start-up (and, according to parameters, when axis is stationary) but uses incremental signals whenever the axis moves.

Solution: whenever you replace an old encoder from Heidenhain request a new one compatible, with both absolute and incremental signals. Look at the end of the Heidenhain catalogue, they try to explain all these issues, with more or less success.

The problem may occur also on Sinumerik 840D SolutionLine with Sinamics S120: you may use encoders with DriveCliq interface (yes, Heidenhain sells also with DriveCliq now), encoders with absolute and incremental signals (and connect the encoder to a SMC20, for example) or encoders with Endat 2.2, without incremental signals (but in this case you must connect the encoder to an SMC40).