On EX2300 series switch, you may observe syslog message 'syspld read failed for address 0x3c'.
This KB describes the meaning of the message.

On EX2300 series switch, error message below is seen intermittently.

Mar 10 06:06:15 Switch lcmd[15418]: LCMD_RD_FAIL: tvp_drv_syspld_read: syspld read failed for address 0x3c, errno=-1
Mar 10 06:06:15 Switch lcmd[15418]: LCMD_STAT_REG_RD_ERR: Unable to read low byte at 0x3c
Mar 13 03:48:58 Switch lcmd[15418]: LCMD_RD_FAIL: tvp_drv_syspld_read: syspld read failed for address 0x3c, errno=-1
Mar 13 03:48:58 Switch lcmd[15418]: LCMD_STAT_REG_RD_ERR: Unable to read low byte at 0x3c

The log would be generated without any specific trigger.
There is no system alarm and the output of "show chassis environment" displays 'OK'.

root@Switch> show chassis environment no-forwarding

Class Item                           Status     Measurement
Power FPC 0 Power Supply 0           OK
      FPC 1 Power Supply 0           OK
Temp  FPC 0 CPU Sensor               OK         37 degrees C / 98 degrees F
      FPC 0 PSU Sensor               OK         35 degrees C / 95 degrees F
      FPC 1 CPU Sensor               OK         37 degrees C / 98 degrees F
      FPC 1 PSU Sensor               OK         34 degrees C / 93 degrees F
Fans  FPC 0 Fan Tray 0 Fan 0         OK         Spinning at normal speed
      FPC 0 Fan Tray 1 Fan 0         OK         Spinning at normal speed
      FPC 1 Fan Tray 0 Fan 0         OK         Spinning at normal speed
      FPC 1 Fan Tray 1 Fan 0         OK         Spinning at normal speed

This log indicates the failure of reading the register value of FAN status.
The log will be seen when the i2c bus is busy.
Since it will happen occasionally, we have a retry mechanism to read it again so there will be no issue.
You can ignore this log if this was seen occasionally.
If you could see this message continuously or similar message which has not the same address with 0x3c, please contact JTAC.