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Error detection time for transmission assurance relays
The power supply of any given PLC fails or is turned off, it takes (as a default value) 6.4 seconds for the
transmission assurance relay of the PLC to be turned off at the other stations. This time period can be
shortened using the SYS1 instruction.
<Programming example of SYS1 instruction>
(SYS1, M PCLK1T1, 100)
Function: Setting SYS1 to change the time that the PC(PLC) link transmission assurance is off from the
default value of 6400 ms to 100 ms.
Keywords: Setting for key word no. 1: PCLK1T1
Permissible range for key word no. 2: 100 to 6400 (100 ms to 6400 ms)
Note:
The setting should not be changed as long as a longer transmission assurance relay detection
time does not cause any problems.
- The SYS1 instruction should be executed at the beginning of the program, at the rise of R9014. The
same time should be set for all linked PLCs.
- The time should be set to a value of at least twice the maximum transmission cycle time when all of the
PLCs are connected to the link.
- If short time has been set, the transmission assurance relay may not function properly. (The shortest
time that can be set is 100 ms.)
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