Despatch Protocol Plus Controller (Heat Only) User Manual

Page 17

Protocol Plus Owner’s Manual

HEORY OF

PERATION

Version 2

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means including graphic, electronic, or mechanical methods or photocopying, recording, or information storage and
retrieval systems without the written permission of Despatch Industries, unless for purchaser's personal use.

· Heating output: The control output is a DC voltage open-collector output which is

time-proportioned and designed to control a heat control device such as a solid state
relay.

· High limit: The high limit output is a form C relay which is energized under normal

operating conditions. If the control senses a temperature higher than the high limit
setpoint, or if there is a sensor error, the high limit relay will de-energize until the
condition is cleared and

Reset

is pressed. When the high limit relay is de-energized,

the heater is disabled.

· Retransmission: The retransmission output is a DC 1 to 5 volt or 4 to 20 ma (DC)

signal that is proportional to the process temperature. The signal can be an input to
other devices such as a chart recorder.

· Relay (four optional outputs): The four form A dry contact relay outputs can be

configured to function as alarms, events, or end of cycle. These outputs can be
utilized in Manual, Timer, or Profile Modes.

Figure 5. Protocol Plus Controller with Rear Cover Removed, Showing Locations for Optional
components.