Campbell Scientific RF400/RF410/RF415 Spread Spectrum Radio/Modem - Manual (Page 53)

F-1
Appendix F. Datalogger RS-232 Port to
RF400 Series Radio
A connection from RF400 RS-232 port to CR23X or CR5000 RS-232 port
requires a 9-pin male to 9-pin male null-modem cable. This cable is available
as CSI Item # 14392.
A 12-Volt Field Power Cable (Item # 14291) or AC adapter (Item # 15966)
must be installed to furnish 12 V to the “DC Pwr” connector on the RF400.
The RF400 can operate with Active Interface in either the Auto Sense mode
(default) or in the RS-232 mode with this configuration.
With the CR23X, the *D 12 “--” setting (to turn datalogger RS-232 port on) is
not required.