COMMERCIAL IN CONFIDENCE
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DESCRIPTION
This document describes the interaction between a CAL Controller with the communications option
fitted and a PC/PLC attached to the bus and acting in a command mode.
There are fundamental limitations placed on the interactions. These arise from the intrinsic properties
of the CAL controllers, with just three control buttons and a multi-level menu with increment or
decrement value change process.
The standalone CAL controllers currently perform a verification on each change to ensure that illegal
values (e.g. ones outside the limit range for a particular thermocouple, etc.) are not accepted .The PC
application needs to replicate the verification checks that the CAL controllers would perform before
transmitting the new data out over the bus to the instrument. The CAL controllers assume that the
values they receive have been checked against limits and are valid - no further verification is carried
out. Upon receipt of the new values and an exit program mode sequence the CAL controllers write the
new values to memory and then restart.
_Copyright Cal Controls Ltd 1999. All rights strictly reserved. No part of this documentation shall be
reproduced ,stored in a retrieval system, or copied in any form, without prior written permission from
Cal Controls Ltd. Every effort has been taken to ensure the accuracy of this specification. However due
to our policy of continuous development to improve our products, this could without notice, result in
amendments or omissions to this document. Neither is any liability assumed for damage, injury, loss,
or expenses resulting from the use of this document.
