On Wed, 16 Feb 2011, jocamo5 [..] ... wrote:

> Fine, but then, how I can make a real time controller for robots without a encoder driver (not supported by Comedi) in your software? Would I have to implement the interface "EncoderInterface" to use?

Indeed, as I mentioned in my first answer.

The best long-term solution for the community would be that you write a
driver for Comedi, since the Comedi-Orocos integration exists already.

Herman

On Wed, 16 Feb 2011, S Roderick wrote:

> On Feb 15, 2011, at 13:55 , Herman Bruyninckx wrote:
>
>> On Tue, 15 Feb 2011, jocamo5 [..] ... wrote:
>>
>>> Hello.
>>>
>>> I am doing a project with Orocos, and I need an analog output card and a encoder card. The analog output works successfully integrated into Orocos, using the class "ComediDevice" (and the card PCI-1720 by Advantech) but I can't integrate the encoder card.
>>>
>>> I've looked at the list of "Supported Hardware" (http://www.comedi.org/hardware) and any two encoder cards appear in the list. The cards I have are:
>>>
>>> -PCI-1784 (Advantech)
>>> -PCI-QUAD4 (Measurement Computing)
>>>
>>> Is there any way to use these cards with Orocos?
>
> We have used the Comedi support in Orocos along with IIRC the AnalogIn/Out classes, to read devices using Comedi-supported DAQ cards. It was a little bit of work, but not too bad.
>
>>> What encoder card can be used with Orocos?
>>>
>>> Help!
>>
>> Orocos is not about interfacing hardware, and we should keep it that way.
>> Other projects (such as Comedi) focus on the hardware interfacing, and
>> that's a perfect match: let each project do its own thing, and do it well;
>> and make sure the different projects are interoperable. But it is our
>> policy not to start our own library of hardware drivers; that would lead to
>> unmaintainable pieces of code. We have defined some generic "HAL
>> interfaces", but we do not want to focus on providing drivers. There are
>> exceptions, such as Comedi, Can and EtherCat, but that's because these are
>> such large scale projects, where one single Orocos effort provides access
>> to thousands of devices.
>>
>> If you have already a driver for your encoder, just wrap it in the generic
>> "EncoderInterface" API
>> <http://people.mech.kuleuven.be/~orocos/pub/stable/documentation/rtt/v2.x/api/html/classRTT_1_1dev_1_1EncoderInterface.html>,
>> or contribute it to Comedi as a new encoder driver.
>
> One of the benefits of Orocos is that there _are_ existing integrations with CORBA and Comedi (amongst others). Such integrations demonstrate maturity and usefulness of a product, and prevent users reinventing the same thing again and again. These should be part of the Orocos _ecosystem_ (as should reference integrations with GUI toolkits). These are critical items needed when using Orocos within a system.
>
> We can certainly discuss/argue whether such things go in RTT or in some other part of Orocos, but I am definitely against removing them.

Who suggested to _remove_ these CORBA and Comedi bridges...? :-) I
definitely not. For the same reasons as you mention: being interoperable
with other large and healthy eco-systems is a plus, and new contributions
should preferably being done in one of the ecosystems, and not in a ad hoc
way in one of them.

> S

Herman