The A100 is a Null Modem Adapter that attaches to either a PS100 or a CH100. When used with the PS100, the PS100/A100 combination provides both 5 and 12 Vdc sources for powering peripherals and external devices at non-datalogger sites such as phone-to-RF base stations.
The CH100/A100 combination is used when it is desirable to use a BP12, BP24, or user-supplied battery at a non-datalogger site.