Greenhouse Datalogging Advice Sought

John E. Austin jea1 at cornell.edu
Wed Jan 17 16:20:36 EST 1996


Sorry if this is a FAQ or off-topic.

I am running a greenhouse temperature logging and alarm system (486 w/
Labtech Notebook, HP VXI Mainframe w/ Command Module, Multimeter, and
several thermocouple and millivolt multiplexers).

We¹ve been having some extremely weird communications timeouts between the
486 and the HP, possibly due to some sooty black gunk that has gotten into
the equipment.  Repair options look pretty expensive and involve a fair
amount of downtime.  I¹m doing what I can to keep the system going.

For the long term, however, I¹ve been asked to look into cost-effective
replacement options.  Would any of you kind people out there be willing to
share (via followup or email) your experience w/ temperature logging and
alarm devices?

Our essential specs include:

1.  Poll and record to DOS-readable disk readings from 20 thermocouples
and about 10 millivolt inputs once every 5 minutes, 24/7, w/ highest
reliability.  Provide a realtime display of these readings.
2.  Check each input against customizable high and low boundaries.
3.  Should any channel go out of bounds, the device or system needs to
close 2 contact closures (local and remote alarm).  We also need to be
able to easily identify which channel has gone out of bounds, even after
the temperature has returned to in-bounds.

Nice, but not essential, specs:

1.  Capture and hold 24hour min and max for each channel.
2.  Self-rebooting.  Priority placed on continuing monitoring and
alarming, rather than on crashing when one datapoint is missed.

Any help here would be greatly appreciated.  If there seems to be
interest, I will summarize and post.



John E. Austin  (jea1 at cornell.edu)
Computer Graphics Specialist / Network Manager
Boyce Thompson Institute for Plant Research at Cornell
Ithaca, NY

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