Mitsubishi Electric QD77MS User Manual page 7

The input devices and data registers assigned to the link will hold the data previous to when
communication is terminated by an error, etc. Thus, an error correspondence interlock program
specified in the instruction manual must be used.
Use the interlock program specified in the intelligent function module's instruction manual for the
program corresponding to the intelligent function module.
When connecting GX Works2 with the CPU module or connecting a personal computer with an
intelligent function module to modify data of a running programmable controller, configure an
interlock circuit in the program to ensure that the entire system will always operate safely.
For other forms of control (such as program modification or operating status change) of a running
programmable controller, read the relevant manuals carefully and ensure that the operation is
safe before proceeding. Especially, when a remote programmable controller is controlled by an
external device, immediate action cannot be taken if a problem occurs in the programmable
controller due to a communication failure. To prevent this, configure an interlock circuit in the
program, and determine corrective actions to be taken between the external device and CPU
module in case of a communication failure.
For the operating status of each station after a communication failure, refer to the "MELSEC-Q
QD77GF Simple Motion Module User's Manual (Network)". Incorrect output or malfunction due to
a communication failure may result in an accident.
Do not write any data to the "system area" of the buffer memory in the intelligent function module.
Also, do not use any "use prohibited" signals as an output signal from the CPU module to the
intelligent function module.
Doing so may cause malfunction of the programmable controller system.
To set a refresh device in the network parameter, select the device Y for the remote output (RY)
refresh device. If a device other than Y, such as M and L, is selected, the CPU module holds the
device status even after its status is changed to STOP.
If a communication cable is disconnected, the network may be unstable, resulting in a
communication failure of multiple stations. Configure an interlock circuit in the program to ensure
that the entire system will always operate safely even if communications fail.
Failure to do so may result in an accident due to an incorrect output or malfunction.
(3) Transportation and installation
Shut off the external power supply (all phases) used in the system before mounting or removing a
module. Failure to do so may result in electric shock or cause the module to fail or malfunction.
DANGER
DANGER
A - 5