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19 TEST FUNCTION
19.1 External Input/Output Forced On/Off Function
Precautions
The following describes precautions for using the external input/output forced on/off function.
• Multiple engineering tools connected to the network can be used to register forced on/off for the same CPU module. In this
case, note the following.
• If a direct device is used in a program, forced on/off registration is reflected when an instruction is executed.
When X0 is forcibly turned off
• When the external input/output forced on/off function is executed while the program of high-speed internal timer interrupt
(I48, I49) is executed, the interval of programs of high-speed internal timer interrupt is short, and a large number of forced
on/off is registered, the scan time will increase and a WDT error may occur.
• Execution of interrupt programs which are executed at a fixed scan may delay depending on the number of forced on/off
registrations and the number of refresh points of each refresh processing.
• When forced on/off is registered in the multiple CPU system configuration, registration is allowed for input/output devices
*2
and external outputs regardless of the out-of-group I/O fetch setting
*1
. Note, however, that the devices of other CPU
modules and the external outputs controlled by other CPU modules are not turned on or off even if forced on/off is
registered from the host CPU for the external outputs controlled by other CPU modules. Only the devices of the host CPU
module are turned on or off.
*1 For the out-of-group I/O fetch setting, refer to the following.
Page 336 Out-of-group I/O fetch setting
*2 Except when the on/off state of the input/output devices is changed by using the output instruction
• In redundant mode, when reflecting forced on/off registration information in the first scan is required, start the standby
system in the STOP state, and switch it to the RUN state after checking that the forced on/off registration information of the
control system is reflected to the standby system. When the standby system is powered on while the control system is
operating, forced on/off registration information may not be reflected in the first scan if the standby system is started with its
RUN/STOP/RESET switch set to the RUN state.
• When reflecting the external input/output forced on/off function to the standby device in a redundant system with redundant
extension base unit, perform tracking transfer for the device.
• The forced on/off state registered last is handled as the on/off state of input/output devices.
• Since the on/off state displayed in engineering tools may differ from that of the CPU module, update the on/off state displayed in engineering tools.
When the input device (X0) is used When the direct input device (DX0) is used
Set X0 by using the SET instruction.
Turn on X0 because the SET instruction is being executed.
Set X0 by using the SET instruction.
Reflect the registered off information.
Turn off X0 although the SET instruction is being executed.
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