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Talking to the Omega controllers is fairly straightforward, plain
serial communications.<br>
<br>
On 3/6/2012 4:43 PM, Elliott Wolin wrote:
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Hi,<br>
<br>
The CDC needs 10 thermocouples, see below.<br>
<br>
I found a 1734-IT2I 2-channel Point I/O thermocouple input module,
about $300 ($150/channel). We could use the Point I/O chassis we
no longer need (because we are replacing the Point I/O RS232
modules with NBX Ethernet-to-RS232 gateways) and place it near the
CDC and minimize the thermocouple wire lengths. Five
thermocouple modules will read out 10 thermocouples, incremental
cost around $1500.<br>
<br>
Alternatively we could purchase 10 Dataforth thermocouple modules
(around $150 each maybe?), then get 10 channels of Point I/O
analog input (around $50/channel?) and again use the spare Point
I/O chassis.<br>
<br>
This latter plan is more expensive and I don't see why we need the
additional isolation...the Point I/O chassis with thermocouple
modules is pretty isolated already.<br>
<br>
Alternative strategies? Thoughts? <br>
<br>
At CMU they read the thermocouples out via Omega controllers...I
don't think we want to figure out how to talk to them, but maybe
it's easy...<br>
<br>
Thanks,<br>
<br>
<br>
<br>
-------- Original Message --------
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<th align="RIGHT" nowrap="nowrap" valign="BASELINE">Subject:
</th>
<td>Re: CDC thermocouples</td>
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<th align="RIGHT" nowrap="nowrap" valign="BASELINE">Date: </th>
<td>Tue, 6 Mar 2012 15:18:04 -0500</td>
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<th align="RIGHT" nowrap="nowrap" valign="BASELINE">From: </th>
<td>Naomi Jarvis <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E" href="mailto:nsj@cmu.edu"><nsj@cmu.edu></a></td>
</tr>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">To: </th>
<td><a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:wolin@jlab.org">wolin@jlab.org</a>, Tim
Whitlatch <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:whitey@jlab.org"><whitey@jlab.org></a></td>
</tr>
<tr>
<th align="RIGHT" nowrap="nowrap" valign="BASELINE">CC: </th>
<td>Mark Stevens <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:stevensm@jlab.org"><stevensm@jlab.org></a>,
"Curtis A. Meyer" <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:cmeyer@ernest.phys.cmu.edu"><cmeyer@ernest.phys.cmu.edu></a>,
Gary Wilkin <a moz-do-not-send="true"
class="moz-txt-link-rfc2396E"
href="mailto:wilkin@andrew.cmu.edu"><wilkin@andrew.cmu.edu></a></td>
</tr>
</tbody>
</table>
<br>
<br>
<pre>Hi Elliott and Tim,
We need to measure the temperature at several points inside the gas plenum at each end of the CDC. We were planning to install 10.
We are not heating or cooling the gas so the range of temperatures would be the ambient temperature range inside the magnet. We would need to read out and log the temperatures, alarm limits would be a good idea, I would guess that a reading every 10-15 minutes would be ample (I will check with Curtis). Do you have any other regular monitoring at an interval between 1 and 30 mins?
We have been planning to use thermocouples for a while. If you have any other suggestions for monitoring the temperature then now would be a great time to make them because we are only a few weeks away from the stage when the devices will be installed.
Thanks for your help,
Naomi.
On Mar 6, 2012, at 2:37 PM, Elliott Wolin wrote:
> Hi Naomi,
>
> I don't think we have many thermocouples in our control system, maybe none.
>
> The cryo systems use different technologies, and we may want to use something other than thermocouples for the CDC. Kindly describe what problem you need to solve, the number of measurement points, range of temperatures expected, readout frequency, etc. I'll check with our engineers and techs to see what they think is the best way to integrate CDC temperature measurements into our control system.
>
> I'm assuming here you want to read out the temperatures and display them on operator screens, set alarm limits on them, log them, etc.
>
> You'll have to talk to Tim about lengths, and the length required may depend on what we purchase.
>
> If in the end thermocouples are the best choice we have many options for reading them out. The simplest is to install thermocouple modules in our Dataforth signal conditioning system, then read the Dataforths out via our PLC. Reading out via an Omega controller may not be the best solution as we'd have to do custom programming to talk to the controller.
>
> Thanks,
>
>
> On 03/06/2012 11:45 AM, Naomi Jarvis wrote:
>> Hi Elliott,
>>
>> we would like to order the thermocouples for the CDC. I remember that the CDC data cables are 18m long. Can you give me an estimate of the length that we would need for the thermocouples please? If you can give me the length to the nearest point on the CDC I can do the rest. I would order the same type that we used with the prototype, these came from <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.omega.com">www.omega.com</a>. It is possible to order extension cables for them later on if we need to, it would probably be easier and less expensive to order slightly longer than we need the first time.
>>
>> Am I correct in thinking that you have or will have the thermocouple controllers? The one we used here was CN616TC1 from Omega.
>>
>> Thanks,
>>
>> Naomi.
>>
>> (FYI The thermocouple part # is 5TC-GG-J-20-nn where nn is the length, and I expect the leading 5 means group of 5).
>
> --
>
> Sincerely,
> Elliott
>
>
> ================================================================================
>
>
> Those raised in a morally relative or neutral environment will hold
> no truths to be self-evident.
>
>
> Elliott Wolin
> Staff Physicist, Jefferson Lab
> 12000 Jefferson Ave
> Suite 8 MS 12A1
> Newport News, VA 23606
> 757-269-7365
>
> ================================================================================
>
>
</pre>
<br>
<pre class="moz-signature" cols="72">--
Sincerely,
Elliott
================================================================================
Those raised in a morally relative or neutral environment will hold
no truths to be self-evident.
Elliott Wolin
Staff Physicist, Jefferson Lab
12000 Jefferson Ave
Suite 8 MS 12A1
Newport News, VA 23606
757-269-7365
================================================================================
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