29 PRECAUTIONS ON PROGRAMMING
29.5 Precautions on Access to Intelligent Function Module or External Devices
513
29
29.5 Precautions on Access to Intelligent Function
Module or External Devices
Depending on the timing of system switching cause to be caused, such as power-off, tracking processing is suspended and
device/label data may not be applied to the CPU module in the new control system after the system switching.
Consequently, output data may differ from device/label data of the CPU module of the new control system. In communication
with intelligent function modules or external devices using the output (Y) or buffer memory, programs may not properly
function due to a mismatch in the device data after system switching.
For command output (such as output (Y), startup by writing data to the buffer memory, and clear) to the intelligent function
module and external devices, consider the time taken for tracking the execution condition of command output from the CPU
module in the control system to the CPU module in the standby system.
The following example shows a program that outputs data one scan later after the command output condition is satisfied.
When response input is returned to output
In the following program, turning on M0 turns on the output (Y10) and turning on M10 turns off the output (Y10).
In the CPU parameter, select "Transfer" (default setting) in "Signal Flow Memory Tracking Setting" of
"Redundant System Settings". ( Page 461 Tracking transfer setting for the signal flow memory)
[Without measures]
[With measures]
(2) PLS M1 delays SET Y0 by one scan.
(9) PLS M11 delays RST Y10 by one scan.
Response input (X10)
Output (Y10)
To Next Page
Loading...
