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PID MODULE MAIN FUNCTIONS
Action after Power Is Restored
When the power is restored, every bit of the operation parameter excluding the program hold bit stored in
the data register is maintained. If the power is failed and restored while the PID module performs the
program control, the PID module starts its operation in accordance with the original PID module status
before the power failure as shown in the table below.
Program End
Action
PID Module Status before the Power Failure
Program
Program Control is
Program Control is
Control is
suspended (Hold)
Terminated.
Performing.
Standby
Status (*1)
Terminate
Program Control
Continue
Program Control
(Repeat)
The program control is
started from the Step 0.
The program
control is
continued.
*2, *3
Standby
status is
maintained.
Hold Program
Control
The program hold is
canceled, and the
program control is
continued. *2, *3
The program hold is
maintained. Fixed value
control is performed with
the set point (SP) at the
time that the power is
turned off.
*1: The PID module is in standby status when the control enable bit is on but the program control bit is off. While in
standby status, the PID module performs no control.
*2: While the program control is running, the PID module saves the program control status every 6 minutes after the
program control is started (after the program control bit is turned on). The program control status is also saved at
the start of each step. If the power to the PID module is turned off while the program control is running, the PID
module resumes the program control from the latest saved point.
Step Number
0
1
2
3
10 min
15 min
3 min
6 min
4
Step Time
(1)
Program
Control Status
Saved Point
Elapsed Time
from Program
Control Start
0 min
(2)
6 min
12 min 18 min
10 min
(3)
25 min
24 min
30 min
34 min
28 min
For example, if the power to the PID module is turned off in 7 minutes after the program control is started at step
0, the PID module resumes the program control at the status (1) when the power is restored. If the power to the
PID module is turned off in 4 minutes after the program control enters step 1, the PID module resumes the
program control at the status (2) when the power is restored. If the power to the PID module is turned off in 2
minutes after the program control enters step 2, the PID module resumes the program control at the status (3),
which is the start of step 2, when the power is restored.
*3: To restart the program control from the start of step 0, turn off and on the program control bit (operation
parameter Bit3).
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FC5A MicroSmart PID Module User’s Manual FC9Y-B1283