Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B - Manual (Page 95)

Publication 900-UM007D-EN-E - January 2011
Configuration & Basic Operation 3-25
Auxiliary Output Opening or
Closing in Alarm Note: Refer to Page 5.73, Auxiliary Output * Open in Alarm (* = 1 to 3), for
definition and furhter explanation of open in and close in alarm.
• When “close in alarm” is configured, the status of the auxiliary output is
output unchanged. When “open in alarm” is configured, the status of
the auxiliary output function is reversed before being output.
• Each auxiliary output can be configured independently.
• These configurations are made in the Auxiliary Output 1 to 3 Open in
Alarm parameters (Advanced Setting function group).
• The default is
n-o: Close in Alarm.
• When “open in alarm” is configured for the alarm 1 output, the open in
alarm status is also applied to heater burnout, HS alarm, heater
overcurrent, and input error outputs.
Executing the ON/OFF
Control Method Overview
In the reverse operation ON/OFF control method, the control output (MV)
turns OFF when the controlled temperature (PV) reaches the user-defined set
point. When the control output (MV) turns OFF, the controlled temperature
begins to fall and the control output turns ON again. This operation is
repeated at a certain point. At this time, how much the temperature must fall
before the control output turns ON again is determined by the Hysteresis
(HEAT) parameter. Also, how much the manipulated variable must be
adjusted in response to the increase or decrease in the process value is
determined by the Direct/Reverse Operation parameter.
ON/OFF Control Parameters
Switching between the 2-PID control method and ON/OFF control method
is carried out by the PID ON/OFF parameter (Initial Setting function group).
When this parameter is configured to
pid, 2-PID control is selected, and
when configured to
onof, ON/OFF control is selected.
Table 3.H — Open In Alarm
Auxiliary Output
functions 1...3
Auxiliary Output
Indicators
(SUB1...SUB3)
Open in Alarm ON ON Lit
OFF OFF Not lit