Yang, M. Kamikubota, N. Kikuzawa, N. Sato, K.C. Tajima, Y. JACoW Publishing Geneva, Switzerland 2673-5512 978-3-95450-237-0 10.18429/JACoW-PCaPAC2022-WEO22 English 8-11 timing power-supply operation PLC controls Contribution to a conference proceedings 2023 2023-02 https://doi.org/10.18429/JACoW-PCaPAC2022-WEO22 https://jacow.org/pcapac2022/papers/weo22.pdf Japan Proton Accelerator Research Complex (J-PARC) timing system has been in operation since 2006. Over the past 16 years, there were trigger-failure events, and some of which seriously affected the operation of J-PARC ac-celerator, especially at Main Ring. To troubleshoot the source of such events more quickly, we decided to devel-op a timing read-back system to read back distributed timing signals at the device side. A PLC-type triggered scaler module was developed as a key of the system. It can count number of pulses in an accelerator cycle and store the counts in a momentary array. Using the module, customized read-back applications for various timing-related signals have been developed: (a) read-back a 25-Hz trigger clock, (b) read-back a pulsed bending magnet trig-ger, (c) read-back a magnet power-supply trigger. These applications were implemented successfully in J-PARC Main Ring, and demonstrated as countermeasure against past trigger-failure events. More details will be given in the paper.