How to Set Zero Point of Absolute Encoder and to Convert Steps to Angle

Hi,

You'll find attached a simple program that I found on internet, which purpose is to measure steps and velocity using profinet absolute encoder.

Is it possible to set reference point to it using an HMI panel, and how to convert steps to degrees/angle.

I suppose this program is more-less universal for all absolute profinet encoders, since it uses a standard telegrams.

Thanks

The conversion of the encoder value to an angle depends on its resolution in points/revolution and the reduction ratio present in the kinematics. All data known only to the person concerned. The rest is trivial mathematics.

For the reference zero, I usually use an offset stored in the PLC, with an adjustment button on HMI, so that even if the device is replaced, anyone can redo that reference procedure without any particular need for mechanical centering or related to the bus or component used.

Is it possible to set zero point via HMI using WRREC? Which of system constants in picture should be used as WRREC ID, I read that it should be Hw-SubModule type in one place, but HW_IO type in other.

I didn't succeed to implement it, and I couldn't find how to do so (information is fragmented, and I am not even sure it is possible).

Is it so hard to check and modify program I uploaded?

milos23

Is it possible to set zero point via HMI using WRREC? Which of system constants in picture should be used as WRREC ID, I read that it should be Hw-SubModule type in one place, but HW_IO type in other.

I didn't succeed to implement it, and I couldn't find how to do so (information is fragmented, and I am not even sure it is possible).

Is it so hard to check and modify program I uploaded?

 You should read the encoder manual, how the preset set is done. Usually there is a bit in the control word for that. Normally the preset bit is activated for ~40ms, for the preset to be accepted.

There's no need for WRREC for setting the preset for the encoder.

I read it already, I don't know to manage these bits yet.

Control word description in attached, can you explain how to manage it?

Here is TR 582 series user manual:

https://easyupload.io/tgb5wd

milos23

I read it already, I don't know to manage these bits yet.

Control word description in attached, can you explain how to manage it?

Here is TR 582 series user manual:

https://easyupload.io/tgb5wd

 On page 143 of that manual, is explained how to do the preset with control word.

I read all of that, the problem is that I never done such a thing, and I don't know how to do it.

I KNOW WHAT HAS TO BE CHENGED:

If you want to help it is easier to change it in program attached instead to explain me what I know already. This is as far as i could get, I suppose that bits 11 and 12 should be reseted to 0, but I don't know how to correctly address encoder, ""Encoder Control DB".Encoder_Control_Word.%X10" is tag with number of bit 11, but I don't know how to add encoder to it.

It uses telegram 83 as in the picture. Program works, it measures pulses, pulses/s and rpm, third network is not part od the program, it is attempt to address bites by me. 

Here si the original page of the program, Italian guy uses TR's profinet ancoder similar to mine:

https://www.gtronic.it/test/index.php/encoder-esempi-e-esercizi-testati-dalling-gottardo/

It seems that this encoder has SSI as second interface. I saw an FB made to use SSI interface with G120C or something alike, but I don't know can it be used to read parameters, and set zero point, if not used with such a drive.

Is CxEPN2~PNO_Encoder_Profile_1 Hw_SubModule 277 (hardware identifier) the one that has to be addressed to read encoder's parameters (there is at least 6 Hw-SubModule possitions related with encoder)?

Can RDREC FB read encoder's settings, is it possible to make a static tag of array type which will include all necessary bits to be read?