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>
> > >
> > >
> > >
> > >
> > >
> >
> >
>
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