Vaisala RDP100 - Manual (Page 11)

Wiring HMDW110 with RDP100
You must always connect the humidity measurement current loop (HUM,
terminals 5 and 6) to power the transmitter. Connecting the temperature
measurement current loop (terminals 7 and 8) is optional.
Connect the RDP100 Remote Display Panel using terminals 1 ... 4. The
HMDW110 series transmitter provides both power and data to the RDP100.
Note: When using the RDP100 with HMDW110 series transmitters,
remove the jumper on the RDP100 component board.
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