| CPC G05B 19/058 (2013.01) [G05B 2219/14055 (2013.01)] | 7 Claims |

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1. A trigger relay unit in a programmable controller, the trigger relay unit being connectable to a plurality of detectors to detect a trigger to log control data about device control, the trigger relay unit comprising:
processing circuitry to
receive a first trigger signal indicating the trigger from a first detector of the plurality of detectors, and
transmit the first trigger signal to a second detector different from the first detector when the first trigger signal is received,
wherein the processing circuitry excludes, from a transmission target, a second trigger signal different from the first trigger signal and received in a period from when the first trigger signal is received to when the processing circuitry completes transmitting the first trigger signal.
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