Experimental Physics and
Industrial Control System

"Mark Rivers" <[email protected]> · Thu, 2 Feb 2006 15:03:01 -0600

Folks,

One thing I did not point out in my message about the Keithley 2700 is
that it is available with an optional Ethernet interface, which would be
advantageous for noise and distance.

Mark

> -----Original Message-----
> From: Al Honey [mailto:[email protected]] 
> Sent: Thursday, February 02, 2006 3:02 PM
> To: Mark Rivers; Josh Stein
> Cc: TechTalk EPICS
> Subject: RE: Cost effective solution for monitoring a large 
> number of temperatures
> 
> Hi All
> 
> After many years of battling with serial devices in a noisy 
> environment
> I now tend towards devices which have an option for enabling 
> a protocol
> and/or a checksum or CRC. Doing that allows detecting and tossing bad
> data, which is not feasible with pure ASCII devices. We have some
> devices at the Keck observatory that occasionally get reprogrammed
> simply from single bit changes in the data stream (distance is many
> hundreds of feet and communications must pass through slip 
> rings, which
> are brushes dragging across copper strips)!
> 
> I do not know if the Keithley units have such features but...
> 
> 
> AH
> 
> 
> -----Original Message-----
> From: Mark Rivers [mailto:[email protected]] 
> Sent: Thursday, February 02, 2006 10:48 AM
> To: Josh Stein
> Cc: TechTalk EPICS
> Subject: RE: Cost effective solution for monitoring a large number of
> temperatures
> 
> Hi Josh,
> 
> I don't have hard numbers for the 2700.  On the older 2000 with a 10
> channel card we can get a little faster than 1Hz if all 10 
> channels are
> active I think (=10 readings per second). They are mechanical switches
> for selecting the active input.
> 
> Mark
>  
> 
> > -----Original Message-----
> > From: Josh Stein [mailto:[email protected]] 
> > Sent: Thursday, February 02, 2006 2:16 PM
> > To: Mark Rivers
> > Cc: TechTalk EPICS
> > Subject: Re: Cost effective solution for monitoring a large 
> > number of temperatures
> > 
> > Hey Mark,
> > 
> >   The Keithly 2700 looks like the ticket. The other solutions 
> > may be a 
> > bit more 'techy' but I'm aiming for COTS as much as 
> possible. It also 
> > appears that Keithly is offering an 40 channel module with 
> > cold junction 
> > compensation now - I'll look into that one. What rates are 
> > you able to 
> > scan this beast at? I imagine it is hardware bound.
> > 
> > Thanks,
> > <josh>
> > 
> > Mark Rivers wrote:
> > 
> > >Hi Josh,
> > > 
> > >In synApps we support the Keithley 2700.  Each of those 
> > units takes 2 cards for a total of 40 thermocouples.  It 
> > costs about $2K, so $50 per thermocouple.  It can be extended 
> > with external multiplexors, but EPICS support would need to 
> > be written for those.
> > > 
> > >Mark
> > > 
> > >
> > >________________________________
> > >
> > >From: Josh Stein [mailto:[email protected]]
> > >Sent: Thu 1/19/2006 9:03 AM
> > >To: TechTalk EPICS
> > >Subject: Cost effective solution for monitoring a large 
> > number of temperatures
> > >
> > >
> > >
> > >Controls experts,
> > >
> > >  In the undulator hall of the LCLS we expect to monitor (what I
> > >consider) a large number of temperature points (on the 
> order of about
> > >300). My past experience with thermocouples has been local 
> > installations
> > >of between one and eight data points. It would be easy to 
> just scale
> > >that solution by a factor of 40, but I have to believe 
> there are more
> > >cost effective solutions.
> > >
> > >  Can anyone with experience in this regard please point me 
> > in the right
> > >direction? I'm looking for hardware that is, of course, 
> > EPICS compliant.
> > >
> > >Thanks,
> > ><josh>
> > >
> > >
> > >
> > >  
> > >
> > 
> > 
> 

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System