Troubleshooting Of Slave Module - Mitsubishi Electric MELSEC-Q Series User Manual

9.4

Troubleshooting of Slave Module

This section describes the troubleshooting of the slave module.
(1) When I/O data and parameter data cannot be checked
Check the FROM/TO instruction
issued by the program using the
programming tool.
Check that the LINK LED on the
slave module is flashing.
Check that the RDY LED on the slave
module is on.
(2) When the I/O data and parameter data of the slave module is unstable
Check the connection of the
terminating unit.
Check the total length of the
transmission cables (D, G).
Check the specifications of the
transmission cables (D, G).
Check the voltage range of the
24VDC external power supply.
Check that the slave module does not
have the same address as the
addresses of other slave modules.
Check the FROM/TO instruction
issued by the program using the
programming tool.
Check that two or more master
modules are not connected within
one AnyWire DB A20 line.
Check that master modules of
different series are not connected
within one AnyWire DB A20 line.
Check that a master module and the
AnyWire DB A20 bridge module are
not connected within one AnyWire
DB A20 line.
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Item
• Check that the buffer memory map of the programmable controller device and the
master module assigned by the MOV instruction or the FROM/TO instruction is
appropriate.
• Check that the CPU module is in the STOP state. Slave module cannot output
data when the CPU module is in the STOP state.
If the LINK LED of the slave module is not flashing, check that there is no
disconnection, short-circuit, incorrect wiring, or poor contact in the transmission
cables around the slave module.
In addition, check that the transmission speed setting of the slave module is same
as that of the master module.
If the RDY LED on the slave module does not turn on, a power supply error has
occurred.
Possible causes are disconnection of the power cable, short-circuit, and shortage of
the power supply voltage.
Check the wiring, installation method, and power supply voltage of the slave module.
Item
Pay attention to the polarities of the terminating unit and connect it correctly.
Adjust the total length of the AnyWire DB A20 system to be within the specification
range.
• Check that the transmission cables (D, G) have the specified type, wire diameter,
and tightening torque to the terminal block.
• Do not run multiple transmission cables (D, G) using a multicore cable.
Adjust the power supply voltage of the 24VDC external power supply to be within the
rated value (21.6 to 27.6VDC).
Set a unique address in the slave module.
Check that the buffer memory map of the programmable controller device and the
master module assigned by the MOV instruction or the FROM/TO instruction is
appropriate.
Connect only one master module within one AnyWire DB A20 line.
Connect only one master module within one AnyWire DB A20 line.
Connect either one master module or one AnyWire DB A20 bridge module within
one AnyWire DB A20 line.
Action
Action