On 15 Dec 2008, at 14:42, Peter Soetens wrote:

> On Monday 15 December 2008 14:25:41 Ruben Smits wrote:
>> Hi,
>>
>> since the comedi support in ocl moved to comedi-0.8 i was updating
>> our
>> robots hardware components, and apparently the positionSet() on a
>> ComediEncoder has no effect. I know that the ComediEncoder was one of
>> the devices that changed most between comedi-0.7.x and comedi-0.8, so
>> probably something went wrong there.
>>
>> I'll try to find out why it does not work anymore. I'm just reporting
>> that there is probably something broken in the ComediEncoder code.
>
> What changed is that in 0.8, an encoder is a subdevice instead of a
> channel
> and the channel(s) holds the counter value. You can read and write
> to such a
> channel (with comedi_data_read/write), but I don't know if this is
> race-safe
> or not.

I checked the code of comedi and i found that is is not safe to write
a value to one of the channels of a counter submodule after is was
armed. This is the case for me.

Apparently the value of a data_write command is not set to the counter
after it was armed. I assume that i was just using the comedi counter
in a wrong way before. This also means that the code of ComediEncoder
should be slightly changed to cope with this.

Ruben

>
> Peter
>