Watlow Electric Revision 5 - Manual (Page 8)

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Configurations can start with only the PROCESSOR I/O MODULE to provide 32
time proportioning or on/off open loop control outputs. For closed loop control,
simply add an ANALOG INPUT MODULE, either reed relay for 16 inputs, or
solid state for 32 inputs. A plug in ANALOG OUTPUT MODULE provides 16
analog control outputs.
Systems can be matched to different applications by combining the following
modules:
1.2.1 PROCESSOR I/O MODULE: The on board microprocessor
performs all necessary control calculations, on-line analog calibration,
system self test, thermocouple compensation and linearization, and
communication to the host computer. This module contains the
communications interface, 32 time proportioning or on/off control outputs,
24 digital outputs, and 16 digital inputs.
Powerful Control: The SYSTEM 32 features a digital control algorithm
that allows each loop to be independently defined. Control outputs can be
set for closed loop or open loop with computer setting of the output level.
Switching between open loop and closed loop control can be initiated with
bumpless transfer. Closed loop control modes can be selected as: on/off,
proportional only [P], proportional with integral [PI], or full PID. In
addition, each output can be selected as reverse [heat] or direct [cool] acting
and a programmable digital output filter can be used to further match each
loop to the process conditions.
Unique Control Output Flexibility: Total control flexibility is assured
since each control output can be easily selected from the computer to match
individual process needs. The unique ANAFAZE design offers: on/off,
Cycle Time Proportioning, or Distributed Zero Crossing. Further flexibility
is included since each output can be set as reverse or direct acting. When a
process requires high power or the use of contactors, the SYSTEM 32 Cycle
Time Proportioning outputs are automatically balanced to minimize the
peak power consumption. For processes with solid-state power switching,
the Distributed Zero Crossing outputs provide the smoothest application of
control power.
Open Heater Detection: The SYSTEM 32 measures the current flowing in
each heater or other time proportioning output circuit to ensure that open
heaters and stuck relays are detected.
Protected Memory: Setpoints and other control parameters entered from
the computer are stored in non-volatile memory eliminating the need to re-
enter these parameters after a power failure.
Communication Monitor: A communications monitor can be enabled that
will turn off all control outputs after a selectable time period if no
communication is received form the host computer.