Sequence Programs For Safety Observation On Plc Cpu - Mitsubishi Electric MELSEC Q Series Programming Manual

2 SAFETY OBSERVATION FUNCTION

2.2 Sequence Programs for Safety Observation on PLC CPU

PLC CPU
Machine control
sequence program
User safety
sequence program
Safety signal
comparison
sequence program
Speed monitoring
sequnce program
communication
sequence program
This section describes the procedure that the Motion CPU transfers the sequence
programs for safety observation to PLC CPU and executes the comparison.
(1) Transfer of sequence programs for safety observation
The sequence programs for safety observation is embedded in Motion CPU
system. The Motion CPU transfers the program to PLC CPU at the Multiple CPU
system start.
The program is structured by the safety signal comparison sequence program
(Program name: SSU_CMP), speed monitoring sequence program (Program
name: SLS_CMP), and safety communication sequence program (Program
name: SNT_CMP).
If the speed monitoring function is not to be used, the sequence program will not
be transferred.
If the safety communication function is not to be used, the sequence program will
not be transferred.
Write user
sequence
program
GX Works2/GX Developer
Transfer at starting up
the controller
Compare at startup
Safety
and more than 24-hours
continuous operation
(2) Comparison of sequence programs for safety observation
After the sequence program is transferred to PLC CPU, the Motion CPU reads
the sequence program from PLC CPU and compares the program with the
original program to check if the sequence programs for safety observation has
been transferred correctly. This check is executed every 24 hours (in case of 24-
hours continuous operation) and at the start.
The shutoff signal will not be turned ON until the sequence programs for safety
observation is confirmed as normal after the power ON.
Motion CPU
Write user
sequence
Machine control
program
sequence program
User safety
sequence program
Safety signal
comparison
sequence program
Speed monitoring
sequnce program
Safety
communication
sequence program
2 - 3
Write user
Motion
program
MT Developer2
PLC CPU sequence programs
for safety observation
(Automatic creation at starting up)