### Four-Wire Direct Concentrator Wiring

Host Adapter or Concentrator "Remote" Port (HD-15 Male) |  | Concentrator "Host Adapter" Port (HD-15 Female)
--- | --- | ---
Signal | Pin | Pin | Signal
RxD- | 1 | Connected to | 1 | TxD-
RxD+ | 2 | Connected to | 2 | TxD+
TxD- | 6 | Connected to | 6 | RxD-
TxD+ | 7 | Connected to | 7 | RxD+
GND | 12 | Connected (via shield) to | 12 | GND

In the Four-Wire Direct (EIA-422) wiring mode, the clock signals are encoded with the receive and transmit data signals, so only two twisted pairs are required.

The Four-Wire Direct cable is a twisted pair cable with a male HD-15 (high-density DB-15) connector at one end and a female HD-15 at the other end. The cable should be shielded, and the shield must be connected to the HD-15 connector shell at both ends.

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