To enable tracing of register reads, select the Tracing → Trace values read checkbox.

To enable tracing of register writes, select the Tracing → Trace value written checkbox.

If tracing is enabled, each read or write of a defined register (see Registers and File Registers) is traced as a single line in the log. Each line begins with the time of the read or write. The time is followed by the character 'R' for a register read or 'W' for a register write. This is followed by the slave ID, the register address and the value read or written. For example (with message tracing also enabled):

17:41:12.272: < transid 8 slave 1 pdulen 5 func 3: 00 11 00 03
17:41:12.273:       Request: Read Holding Registers: address 17, count 3
17:41:12.276: > transid 8 slave 1 pdulen 14 func 3: 0c 00 00 00 1d 00 00 01 55 41 ...
17:41:12.277:       Response: Read Holding Registers: byte count 12, data bytes 12
17:41:12.281:         R  1  17  29
17:41:12.282:         R  1  18  341
17:41:12.284:         R  1  19  29.230000

The register address for ordinary registers is a "model" address (see Address mapping). The register address for a file register consists of the file number and register number separated by ':'. For example (with message tracing also enabled):

17:37:08.552: < transid 6 slave 1 pdulen 16 func 20: 0e 06 00 03 00 03 00 03 06 27 ...
17:37:08.553:       Request: Read File Record
17:37:08.557: > transid 6 slave 1 pdulen 16 func 20: 0e 07 06 85 2b 00 24 03 75 05 ...
17:37:08.558:       Response: Read File Record
17:37:08.565:         R  1  3:3  34091
17:37:08.567:         R  1  3:4  36
17:37:08.568:         R  1  3:5  885
17:37:08.569:         R  1  10000:102  4486
17:37:08.570:         R  1  10000:103  20371