
7. TROUBLESHOOTING
B–63665EN/01
334
This alarm is issued if a fault is detected in the PMC.
The probable causes include an I/O link communication error and a
defective PMC control circuit
The I/O Link is a serial interface that connects the CNC to various I/O
devices and allows transfers of I/O signals between devices at high speed.
When multiple devices are connected using the I/O Link, there forms a
relationship that a certain device is a master and the other devices are
slaves. The states of the input signals from the slaves are transferred to
the master at fixed intervals. The output signals from the master are
transferred to the slaves at fixed intervals. In a CNC system, the master
is the CNC (motherboard or main CPU board).
The I/O signals transferred via the I/O link can be used with the PMC
Ladder.
Master station (CNC)
Slave station #0
Slave station #1
Group 0
Group 1
Up to 16 groups
If alarm 950 is issued, displaying “PC050” on the screen, an I/O link
communication error may have occurred.
Screen display example
SYSTEM ALARM
950 PMC SYSTEM ALARM
PC050 NMI SLCxx:yy
In this screen display example, the cause of the alarm can be estimated
using xx:yy. xx and yy are hexadecimal representations.
7.30
ALARM 950
(PMC SYSTEM
ALARM)
Causes and actions
D Connecting the I/O Link
D I/O Link communication
error PC050