Furuno to B&G NMEA 0183 connection

[bewitched]

Some help needed please.

I'm trying to interface a B&G FFD with a Furuno MFD via NMEA 0183.

The B&G is all familiar to me Rx+, Rx-, Tx+, GND

The Furuno I'm struggling with. I have: TD-A, TD-B, RD-C and RD-H as options

An internet search reveals:
TD-A in Furuno land = Tx+ in NMEA0183 land
and
TD-B in Furuno land = Tx- in NMEA0183 land

I'm struggling with RD-C and RD-H

Clearly these are Rx but which is Rx+

Can anyone help (no guessing please )

[nigel1]

H = +
C = -

No idea why Furuno use H/C instead of +/-.
If you can, give Furuno tech support a call, I have always found them to be very helpful