3 Part Names and Functions
3 - 44
NX-series Safety Control Unit User’s Manual (Z930)
The test pulse evaluation outputs a test pulse with a specific period on the 24-VDC power line from a
safety output terminal to detect errors in wiring to the externally connected device. This evaluation is
achieved through the Test Pulse Diagnosis parameter.
Test Pulse Diagnosis
The Diagnosis setting determines whether to output a test pulse with a specific period from the
safety output terminal. The parameter determines whether test pulse evaluation is used. The errors
that can be detected are determined by the parameter settings.
Refer to Errors Detected during Self-diagnosis on page 3-47 for the errors that can be detected for
each parameter setting.
Precautions for Correct Use
When the Test Pulse Diagnosis parameter is set to with Test Pulse, OFF pulse signals with a
pulse width of 640 μs are output while the safety output is ON to diagnose the output circuit.
Check the input response time of the connected control device to make sure it will not malfunc-
tion due to these OFF pulses.
The use of dual-channel equivalent outputs lets you control two safety output terminals with one safety
output data from the safety program. If an error is detected in either of the two output terminals, the out-
puts to the external devices are both turned OFF.
• Single Channel
• Dual Channels
This evaluation is achieved through the Single/Dual parameter.
Test Pulse Evaluation
Dual Channel Evaluation
Safety Output Unit
Safety CPU Unit
Safety output terminals
Safety program
execution
Safety output data
Safety process data
communications
I/O port
Device variable
Test pulse evaluation
Safety Output Unit
Safety CPU Unit
Safety output terminals
Safety program
execution
Safety output data
Safety process data
communications
I/O port
Device variable
Test pulse evaluation
Test pulse evaluation