Environmental Test Chamber

[G]

Has anyone made a VI to run a environmental test chamber? What about Ramp,
Soak profile programming?

G

[mikeporter]

This isn't very hard. Who's chamber are you using and what is controller is on it?In general, these things will tak either MODBUS or standard RS232 serial. The documentation for the controller should have a section in it on how to interact with it.In terms of Ramp and Soak operations different controllers handle these operations differently, but in general you send an array of values to the control that define temperatures, ramp times and soak times before the next temperature change. Some controllers will generate triggers to signal external functions that a programmed temperature step has been reached, and the soak has finished.I can possible give you more specifics--including code--if you tell me what controller you are going to be talking to.Mike...

[G]

We would like to eliminate the conroller completely (its its a real old
thermotron and it doesn't work) and build a new Compact Fieldpoint system.
PID tuning is available, but profile programming is the only open issue?


----- Original Message -----
From: "mikeporter"
Newsgroups: comp.lang.labview
Sent: Tuesday, February 25, 2003 9:05 AM
Subject: Re: Environmental Test Chamber


> This isn't very hard. Who's chamber are you using and what is controller
is on it?In general, these things will tak either MODBUS or standard RS232
serial. The documentation for the controller should have a section in it on
how to interact with it.In terms of Ramp and

Soak operations different controllers handle these operations differently,
but in general you send an array of values to the control that define
temperatures, ramp times and soak times before the next temperature change.
Some controllers will generate triggers to signal external functions that a
programmed temperature step has been
reached, and the soak has finished.I can possible give you more
specifics--including code--if you tell me what controller you are going to
be talking to.Mike...
"mikeporter" wrote in message
news:5065000000050000002CD40000-1042324653000@exchange.ni.com...
> This isn't very hard. Who's chamber are you using and what is controller
is on it?In general, these things will tak either MODBUS or standard RS232
serial. The documentation for the controller should have a section in it on
how to interact with it.In terms of Ramp and
Soak operations different controllers handle these operations differently,
but in general you send an array of values to the control that define
temperatures, ramp times and soak times before the next temperature change.
Some controllers will generate triggers to signal
external functions that a programmed temperature step has been reached, and
the soak has finished.I can possible give you more specifics--including
code--if you tell me what controller you are going to be talking to.Mike...

[mikeporter]

The key thing is to approach the design of this controller in a systematic manner. The trickiest thing will be to provide appropriate safety measures. One of the nonobvious things that a dedicated controller provides are safety cutoffs. These cutoffs are purely hardware in nature--in other words they are protecting the system from over- or under-temp conditions regardless of whether the control program is running.

Beyond this requirement, the main thing is to first develop a control application that allows you to specify a target temperature, and ramp time. This basic function will be the foundation that the rest of the control application will build on. In terms of profile programming, if I understand what you mean, that really is a user in
terface issue. You will need to provide some sort of interface that essentially allows the user to "draw" the temperature profile that the chamber is to follow. The code then takes this drawing and converts it into a series of temperature setpoints, ramptimes and temperature soaks.

Mike...