Black Box Async RS232 Extender over CATx, DB9 Female to Terminal Block

The Black Box ME800A-R4 is an asynchronous RS232 extender that moves serial signals far beyond the usual 50 foot boundary. By shifting the link to familiar CATx cabling, it keeps full duplex communication running at data rates up to 115.2 kbps while covering distances that can reach four miles.

This extender fits naturally in industrial control rooms, security installations, building automation closets, and any site where legacy RS232 devices still offer reliable service but sit well away from the nearest computer or controller. Plant engineers can place sensors or PLCs on the production floor yet manage them from a protected office. Security integrators can route access-control panels back to a central rack without pulling expensive specialty cable. Field technicians supporting scoreboards, digital signage, or environmental monitors will appreciate the freedom to position equipment where it works best instead of where the cabling stops.

The unit operates over four wires, and its built-in transformer and optical isolation shield attached gear from ground loops and electrical noise. This protection helps maintain clear, error-free data even in noisy factory or outdoor environments.

Installation is straightforward. A DB9 female connector on one side accepts standard RS232 cables, while a removable terminal block on the other side ties directly into four-wire CATx runs. A flip-top lid lets you switch between DTE and DCE roles in seconds, removing guesswork when matching pinouts. For quick troubleshooting, a front-panel button triggers a loopback test so you can verify continuity and polarity before bringing the link online. Deploy the ME800A-R4 in pairs: one beside the host PC or controller, the other beside the remote device, and the connection is ready.

Because it works with common connectors and adapters, the extender slides easily into existing racks or wall-mount enclosures without forcing a redesign. The result is a clean, cost-effective way to preserve RS232 equipment while enjoying the reach and flexibility of network-grade cabling.

Highlights:

• Extends RS232 signals over CATx cabling up to four miles
• Supports data rates up to 115.2 kbps
• Maintains full duplex communication on a four-wire link
• Transformer and optical isolation protect against electrical interference
• Works with RS232, DB9, and RJ-11 connections through standard adapters
• Flip-top lid enables rapid DTE or DCE selection
• Front-panel loopback test simplifies troubleshooting