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From: Joerg on 14 Apr 2008 09:09
Frank Buss wrote:
> przemek klosowski wrote:
>
>> On Fri, 11 Apr 2008 13:39:07 -0700, Julian Vrieslander wrote:
>>
>>> I'm looking for a simple data acquisition interface that will run on a
>>> Linux PC (Fedora Core 6). The requirements are very simple: 24 bits of
>>> digital output. We need to be able to flip single bits or groups of
>>> bits without causing glitches on unchanged bits. Data rate is slow -
>>> maybe one write every 2 milliseconds.
>> Three USB parallel ports and a minihub? You'd have to check for glitches
>> but it should work.
>
> USB transfers packets in timeslots of 1 ms. I'm still learning the USB
> protocol, but I think if all three USB ports are on the same hub, each
> device will be accessed every 3 ms. And Linux is not a realtime system
> (without additional work), so if the OS thinks it is a good idea to process
> some network traffic, you might lost many milliseconds before the next
> update.
>

Yes, the lower msec range is the gray zone where a streaming mode may be
required. The LabJack has that but I don't know if it can be used that
slow. So far I have only used it at full speed.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: JosephKK on 20 Apr 2008 13:30
On Sun, 13 Apr 2008 00:53:18 -0700, Julian Vrieslander
<julianvREMOVE_THIS_PART(a)mindspring.com> wrote:

>Thanks to David and Joerg for the replies. I'll check into both NI and
>Labjack.
>
>I was aware of the NI products, but a bit hesitant about buying from
>them. It's not their pricing. I do a lot of work with Macs, which they
>used to suppport quite well. But a more recent attempt to get
>assistance with an NI card in a Mac was less rewarding. Their attitude
>to Mac users now seems to be "Use LabView or don't call us...".
>
>Maybe their support for Linux is better.

The last i heard they have _no_ support for *nix.
From: david on 20 Apr 2008 20:52
On Sun, 20 Apr 2008 10:30:59 -0700, JosephKK rearranged some electrons to
say:

> On Sun, 13 Apr 2008 00:53:18 -0700, Julian Vrieslander
> <julianvREMOVE_THIS_PART(a)mindspring.com> wrote:
>
>>Thanks to David and Joerg for the replies. I'll check into both NI and
>>Labjack.
>>
>>I was aware of the NI products, but a bit hesitant about buying from
>>them. It's not their pricing. I do a lot of work with Macs, which they
>>used to suppport quite well. But a more recent attempt to get
>>assistance with an NI card in a Mac was less rewarding. Their attitude
>>to Mac users now seems to be "Use LabView or don't call us...".
>>
>>Maybe their support for Linux is better.
>
> The last i heard they have _no_ support for *nix.

Their web site says otherwise.

From: JosephKK on 20 Apr 2008 22:56
On 21 Apr 2008 00:52:35 GMT, david <none(a)nospam.com> wrote:

>On Sun, 20 Apr 2008 10:30:59 -0700, JosephKK rearranged some electrons to
>say:
>
>> On Sun, 13 Apr 2008 00:53:18 -0700, Julian Vrieslander
>> <julianvREMOVE_THIS_PART(a)mindspring.com> wrote:
>>
>>>Thanks to David and Joerg for the replies. I'll check into both NI and
>>>Labjack.
>>>
>>>I was aware of the NI products, but a bit hesitant about buying from
>>>them. It's not their pricing. I do a lot of work with Macs, which they
>>>used to suppport quite well. But a more recent attempt to get
>>>assistance with an NI card in a Mac was less rewarding. Their attitude
>>>to Mac users now seems to be "Use LabView or don't call us...".
>>>
>>>Maybe their support for Linux is better.
>>
>> The last i heard they have _no_ support for *nix.
>
>Their web site says otherwise.

So it does. That is a welcome change.

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