AN/FCC-100 Multiplexer to Pairgain Campus CSU

Pinout of the field-integration cable connecting an AN/FCC-100 tactical TDM multiplexer DB-25 port to a PairGain Campus CSU DB-25 DTE interface.

Updated:

25 PIN D-SUB MALE 25 PIN D-SUB MALE

25 PIN D-SUB MALE 25 PIN D-SUB MALE

The AN/FCC-100 (also known as the LDMX) is a US military tactical TDM voice/data multiplexer produced by DNE Technologies (later Ultra Electronics DNE Technologies), supporting up to 16 DB-25 female user ports running balanced RS-422/RS-530 signalling at rates up to 2 Mbps. The PairGain Campus CSU is an HDSL-based T1/fractional-T1 channel service unit designed for campus-range local loops over unconditioned twisted pair. This cable connects one DB-25 female user port on the AN/FCC-100 to the DB-25 female DTE port on the PairGain Campus CSU, carrying differential transmit and receive data pairs together with receive clock. The AN/FCC-100 family spans variants (V)1 through (V)9X and is backward-compatible across all revisions.

FCC PortPair Gain
SignalPin
TRANSMIT DATA +2
TRANSMIT DATA -14
RECEIVE DATA +3
RECEIVE DATA -19
RECEIVE CLOCK +17
RECEIVE CLOCK -18

The following pins are looped in the Pair Gain DB-25 connector:

  • 7 (RTS +), 9 (CTS +)
  • 25 (RTS -), 27 (CTS -)
  • 11 (DSR +), 12 (DTR +), 13 (DCD +)
  • 29 (DSR -), 30 (DTR -), 31 (DCD -)

Notes

Both connectors are DB-25. The AN/FCC-100 user port presents a DB-25 female; the PairGain Campus CSU DTE port also presents a DB-25 female, so both cable ends terminate in DB-25 male connectors. All data and clock signals are balanced differential pairs per RS-422/EIA-530-A. The loopback connections on the PairGain side satisfy the modem-control handshake lines (RTS/CTS, DSR/DTR/DCD) locally, removing the need for the multiplexer to assert them.

References

Category:Networking Cables