COM-2PD-PE

PCI Express isolated 2-channel RS-422A/485 serial I/O board with 921,600 bps maximum data rate. Channel-to-channel and bus isolation, surge protection on all signal lines, 128-byte FIFO buffers per channel. Operates as standard Windows/Linux COM ports.

The COM‑2PD‑PE provides two isolated RS‑422A/485 serial ports on a PCI Express board. It supports data rates up to 921,600 bps and includes 128‑byte FIFO buffers for transmit and receive per channel. Full duplex and half duplex operation are supported.

• Channel and bus isolation — 1000 VDC isolation between channels and between PC and bus; eliminates ground loops and noise.
• Surge protection — all signal lines protected against voltage surges; safe for industrial environments.
• High speed — supports baud rates from 30 to 921,600 bps (depending on board revision).
• FIFO buffers — 128 bytes each for transmit and receive per channel; reduces CPU load during high‑speed communication.
• Software control — RTS+, RTS‑, CTS+, CTS‑ lines can be controlled and monitored via software.

The board uses two 9‑pin D‑SUB connectors (CN1, CN2) for serial ports. Pin assignments: TD (even pins +, odd pins –), RD (even +, odd –), RTS (even +, odd –), CTS (even –, odd +). Note that CTS polarity is opposite of other signals.

• Signal polarity — TD, RD, RTS: even pins are +, odd pins are –. CTS: even pins are –, odd pins are + (not a misprint).
• Twisted pair recommended — differential signalling benefits from twisted pair cable for noise immunity.
• Termination — termination resistors can be enabled/disabled via switches (SW2, SW4).
• Data transfer mode — selectable via switches (SW4, SW5) for RS‑422 or RS‑485 operation.
• Board ID — set via SW1 to distinguish multiple boards.

• VCCI Class A — Japanese EMC for commercial/industrial environments.
• FCC Class A — U.S. emissions compliance for industrial use.
• CE (EMC Directive Class A + RoHS) — European conformity.
• UKCA — UK conformity assessed.