SSI ABS Encoder

andypugh wrote:

annhandt09 wrote:

i tried this. The encoder data returned : 0->2047 - 2047 -2046 ...->-1 for 0->4096 datas
Is it correct?

I think it assumes that the data is signed, which is a problem in this case.

I have just realised that the answer is to simply not configure it as an encoder at all...

Use %12U and it should be fine.

andypugh wrote:

annhandt09 wrote:

Hi, i used %12U , then the returning data is 0->1

That's a start, at least.

I can't config "setp hm2_7i80.0.ssi.00.zencoder.scalemax 0.5" para. It's error

What error? Does the parameter exist?

andypugh wrote:

I think that the underlying problem here is that the SSI driver re-uses the smart-serial driver code, so makes assumptions that the input data is like the smart-serial data. In smart-serial the encoders are always signed-int, for example, and that is why %12e is not working with your unsigned encoder.

However, looking at the source
github.com/LinuxCNC/linuxcnc/blob/master...mot2/sserial.c#L1212
It looks like there should be a "scalemax" pin for your zencoder if is is defined as unsigned with %12U

Can you get a pin listing for hm2_7i80.0.ssi* ?
(halcmd show pin hm2_7i80.0.ssi* )

halcmd show pin hm2_7i80.0.ssi.00
Component Pins:
Owner   Type  Dir         Value  Name
    29  bit   OUT         FALSE  hm2_7i80.0.ssi.00.data-invalid
    29  bit   OUT         FALSE  hm2_7i80.0.ssi.00.steps
    29  bit   OUT          TRUE  hm2_7i80.0.ssi.00.steps-not
    29  float OUT    0.01782662  hm2_7i80.0.ssi.00.zencoder ==> z-pos-fbss

PCW wrote:

Scale is not a pin but a parameter so try:

halcmd show param hm2_7i80.0.ssi*

linuxcnc:~ $  halcmd show param hm2_7i80.0.ssi*
Parameters:
Owner   Type  Dir         Value  Name

andypugh wrote:

I don't know why there is no scalemax pin, I do think that there should be.

Which firmware are you using? I might need to load that to test.

As a workaround, you could use a HAL "scale" component to change the 0->1 value that you are currently getting to be the range that you require.