To update the firmware, please refer to Appendix B of the user manual.
http://ftp.icpdas.com.tw/pub/cd/tsl/user_manual/tsl-p4r1_tsl-pa4r1_user_manual.pdf

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Jan.29, 2018, v1.5.2

Chg: Fix spelling error of the web interface.

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Dec.18, 2017, v1.5.1

Chg: Change Modbus table and web display sequence to current combinatorial status value, previous combinatorial status value, 
     current combinatorial status time, and previous combinatorial status time.

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Dec.12, 2017, v1.5.0

Chg: Increase the length of MQTT user name and password to 63 bytes.

Chg: The whole MQTT topics can be specfied by user.

Add: Add previous combinatorial status value, Modbus register 30007

Add: Add current combinatorial status time, Modbus register 30008

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