1) USB DrDAQ Data Logger - User's Guide.
2) PicoLog Data logging software - User's Guide.
3) PicoLog Self-Help Guide.
The most detailed reference to the Auto-Detect resistors can be found in reference 1) above. On page 32 we read:
Auto-Detect Auto-detect resistor is placed between Ground (pin 2) and Signal Detect (pin3). The value of the resitor should be selected from one of the following common values: 1k0, 2k2, 3k3, 5k6, 7k5, 10k. It is necessary to have an auto-detect resistor so that the software can automatically scale the input signal into the property it represents.
Very good, all is well, save that nowhere in Pico publications we can find what "common resistor values" correspond to which "input properties" to be represented.....
Is there perhaps some other Pico publication I have missed?