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Small rectangular beige desktop box with DB9, terminal block, RJ-11 and power ports

Black Box Corporation

Black Box ME800A-R4 Async RS-232 Extender Over CATx

SKU CH-74T5-P8SCB MPN ME800A-R4

Extends asynchronous RS-232 signals up to 6.4 km over CATx cabling with full-duplex operation at up to 115.2 kbps

  • Port count(1) DB9 F, (1) 4-screw terminal block, (1) RJ-11, (1) DC pow
  • Maximum range4 mi. (6.4 km) maximum
  • Transfer speed115,2000 bps at 4000 ft (1219.2m); 57,600 bps at 1 mile (1.6
  • Power adapter115 V AC, 60 Hz +/- wallmount, 9 V DC, 500 mA, 4.5 W maximum
  • HighlightsFull duplex operation over 4-wire CATx Data rate up to 115.2
  • Product dimensions1.5 in × 5.2 in × 5.2 in
  • Extends RS-232 signals up to 6.4 km over CATx
  • Full duplex operation on four-wire CATx cabling
  • Data rate up to 115.2 kbps at shorter distances
  • DB25 male to terminal block for flexible wiring
  • TAA compliant and WEEE certified for regulated projects

Async RS-232 Extender Over CATx

The Black Box ME800A-R4 extends asynchronous RS-232 signals up to 6.4 kilometres over standard 4-wire CATx cabling. It provides full-duplex operation with selectable data rates up to 115.2 kbps at shorter distances. The unit features a DB9 female port, a 4-screw terminal block, an RJ-11 modem port and a DC power jack. It is designed for point-of-sale systems and industrial serial links requiring long-range connectivity.

DB9 and Terminal Block Wiring

Installation uses the supplied 9V DC, 500 mA wall-mount adapter connected to the DC jack. The DB9 female connector accepts a standard serial cable while the 4-screw terminal block terminates the CATx pairs directly without punch-down tools. A common issue is reversing the tip and ring wires on the terminal block, which prevents link establishment. Verifying the CATx cable uses all four conductors and is 24 AWG solid core avoids distance-related data errors.

Sustained Long-Distance Operation

Under continuous load the extender maintains the configured baud rate without throughput degradation. At the maximum 6.4 km range the data rate settles at 9.6 kbps, while 115.2 kbps is sustained up to 1.2 km. The 4.5 W power draw remains constant during extended sessions and the desktop enclosure operates within commercial temperature limits. Backward compatibility with the ME800A-R3 allows mixed deployments without protocol changes.

How it compares

Measured against everything we stock in SFP & SFP+ Transceiver Modules, at today’s prices. Recalculated every night.

Price $153.99
Typical for this category: the median of 1,471 items is $138.99.

Specifications

Product
Brand nameBlack Box
Model nameME800A-R4
Performance
Transfer speed115,2000 bps at 4000 ft (1219.2m); 57,600 bps at 1 mile (1.6 km); 9,600 bps at 4 miles (6.4 km)
Connectivity
Maximum range4 mi. (6.4 km) maximum
Ports & slots
Port count(1) DB9 F, (1) 4-screw terminal block, (1) RJ-11, (1) DC power jack
Power
Power adapter115 V AC, 60 Hz +/- wallmount, 9 V DC, 500 mA, 4.5 W maximum
Size & build
Product dimensions1.5 in × 5.2 in × 5.2 in
Shipping weight0.68 kg
Package size305 × 254 × 203 mm

Questions about this item

How can I verify the extender is working correctly after connecting the DB9 female and terminal block?

Check that the link LED stays solid and that a serial terminal shows clean data at the configured baud rate up to 115.2 kbps over the CATx run.

What comes in the box and which cables or adapters must I source separately?

The unit includes the extender with DB9 female, 4-screw terminal block, RJ-11 port and DC jack; you must supply the CATx cable, a 9 V DC 500 mA power adapter and any DB9 or terminal-block wiring.

Which version should I choose if I need to replace an older ME800A-R3 in a point-of-sale system?

The ME800A-R4 is backwards compatible with the ME800A-R3 and supports the same 4-wire CATx full-duplex operation up to 6.4 km at 9.6 kbps.

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