If you’ve ever worked with legacy Allen‑Bradley PLCs (Programmable Logic Controllers) from the 1990s or early 2000s, you may have come across a mysterious term: .

| Feature | Detail | |---------|--------| | Form factor | PCMCIA Type II | | Protocols | DH+, DH‑485, RIO | | Software | RSLinx (classic), RSLogix 5/500 | | Max nodes (DH+) | Up to 64 | | Cable required | 1784‑PCMK to 1784‑PCM5 (or similar) |

The PCMK card is a card—commonly called a “PC Card”—used to connect a DOS‑based or early Windows laptop to Allen‑Bradley PLCs.

If you need to connect to DH+ or DH‑485 today, consider these alternatives: