Mitsubishi Q Series User Manual

3 - 16 3 - 16
MELSEC-Q
3 SPECIFICATIONS
POINT
(1) When not using the loop disconnection detection function, set the loop
disconnection detection judgment time (buffer memory address: 59, 91) to "0".
(2) Setting the loop disconnection detection dead band will not cause a loop
disconnection if there is no temperature variation of 2
or more when the
control output is provided 100% or 0% at the set value. (Refer to Section
3.5.31.)
(3) If loop disconnection alert occurs frequently despite the normal operation of
sensor, load, and external operation device, check and operate the following
points.
• Check whether or not load (heater) and external operation device (cooling fan,
etc.) have proper efficiency in performance.
If they are deficient, make the setting value of loop disconnection detection
judgment time (buffer memory address: 59, 91) longer than the time required
for varying 2
or 0.2% with manipulated value 100%.
• If using for heating control, check whether the set value has dropped to below
ambient temperature or not.
If so, set the loop disconnection detection dead band (buffer memory address:
60, 92) to prevent an alert occurrence near the ambient temperature.
3.2.9 Data storage on FeRAM function
(1) Data storage on FeRAM
(a) The Q62HLC buffer memory data can be stored onto FeRAM for backup.
The whole write-enabled area of the buffer memory can be backed up.
Refer to Section 3.5 for details of the buffer memory.
Item Buffer memory address (Decimal)
Program control 57, 89
PID constant read command from
FeRAM
62, 94
Automatic backup setting after auto
tuning of PID constants
63, 95
Hold command 201, 217
Command advancing 202, 218
Cascade ON/OFF 176
Write to FeRAM can be used to back up the PID constants set by auto
tuning and the data written directly to the buffer memory using a peripheral
device.
(b) The backed up data is transferred from FeRAM to buffer memory when the
programmable controller CPU is powered on (power is switched on) or
reset.
Hence, PID control can be exercised without data being written when the
programmable controller CPU is powered on or reset.
The program used to set data to the Q62HLC can be eliminated.

Mitsubishi Q Series Specifications

General

Brand	Mitsubishi
Model	Q Series
Category	Control Unit
Language	English