Mitsubishi Electric 800 Series Instruction Manual page 298

PU operation interlock (Pr.79 = "7")
• The operation mode can be forcibly switched to the External operation mode by turning OFF of the PU operation interlock
(X12) signal. This function prevents the operation mode from being accidentally unswitched from the PU operation mode. If
the operation mode left unswitched from the PU operation mode, the inverter does not reply to the commands sent through
external commands.
• To input the X12 signal, set "12" in any of Pr.178 to Pr.189 (Input terminal function selection) to assign the function to a
terminal. (For details on Pr.178 to Pr.189, refer to
• Set Pr.79="7" (PU operation interlock).
• If the X12 signal is not assigned, the function of the MRS signal is switched to PU operation internal signal from MRS
(output stop).
X12 (MRS)
signal
Switching of the operation mode (External, PU, and
ON NET) is enabled.
Output is stopped during External operation.
Operation mode is forcefully changed to the External
operation mode.
OFF External operation is enabled.
Switching to the PU or NET operation mode from the
External operation mode is disabled.

Depends on the Pr.77 Parameter write selection setting and the writing conditions of each parameter. (Refer to
• Functions/operations by X12 (MRS) signal ON/OFF
Operating status
X12 (MRS) signal
Operation
Status
mode
during a
ON→OFF
stop
PU/NET
Running ON→OFF
OFF→ON
during a
stop
ON→OFF
External
OFF→ON
Running
ON→OFF

The mode is switched to the External operation mode regardless of the ON/OFF state of the start signals (STF, STR). Thus, the motor runs
under the External operation mode when the X12 (MRS) signal turns OFF with either of STF or STR in an ON state.

When a fault occurs, the inverter can be reset by pressing
NOTE
• The operation mode cannot switched to the PU operation mode with the start signal (STF, STR) in an ON state even if the
X12 (MRS) signal is ON.
• If the MRS signal is ON and Pr.79 is written to a value other than "7" when the MRS signal is used as the PU interlock signal
during PU operation mode, the MRS signal will act as a regular MRS function (output stop). Also, when Pr.79="7", the MRS
signal becomes the PU interlock signal.
• The logic of the signal follows the Pr.17 MRS input selection setting also when the MRS signal is used as the PU operation
interlock signal. When Pr.17 ="2", ON and OFF in the above explanation are reversed.
• Changing the terminal assignment using Pr.178 to Pr.189 (Input terminal function selection) may affect the other
functions. Set parameters after confirming the function of each terminal.
(D) Operation command and frequency command
page 415.)
Function/Operation
Operation mode
Operation
mode
If frequency and start commands are input from

External external source, the inverter runs by those

commands.

during a stop
External

Running→Output shutoff
Output shutoff→Running
Parameter writing
Parameter writing enabled
Writing of parameters other than Pr.79 is disabled.
Operating status
on the operation panel.

page 251.)
Switching to
PU or NET
operation mode
Not available
Not available
Available
Not available
Not available
Not available
297
PARAMETERS
5
GROUP
D