| 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) |

While it looks like a relic today, the PCMK (PC Card Master Kit) was once an essential tool for thousands of automation engineers. In this post, we’ll cover what it was, why it mattered, and what has replaced it.

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

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’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: .

| Replacement | Pros | Cons | |-------------|------|------| | (USB to DH+) | Fast, USB‑A plug, works with Windows 10/11 | Expensive ($1,500+) | | 1756‑ENBT/DHRIO (ControlLogix bridge) | Ethernet to DH+ conversion | Requires a ControlLogix rack | | ProSoft or Anybus gateways | Flexible, modern support | Additional configuration | | VM with legacy Windows 98/2000 + PCMK | Low cost if you own the card | Slow, driver headaches |

You can use this as a blog post, a LinkedIn article, or a knowledge base entry. The PCMK Card Explained: A Forgotten Key to Industrial Automation