1784-KT-2 1784-KT-1 1784-KT-4 1784-KT-3

The Allen-Bradley 1784-KT is a legacy industrial communication interface module (ISA card) designed to enable personal computers and industrial workstations to connect directly to Allen-Bradley Data Highway Plus (DH+) networks. Developed for PLC-2, PLC-3, and PLC-5 environments, it allows a PC to function as a network node for monitoring, programming, and data exchange.

This module belongs to the classic Rockwell Automation PLC communication ecosystem and is primarily used in older industrial control systems where DH+ networks are still in operation.

Technical Specifications (including Dimensions & Weight)

Parameter	Specification
Product Type	DH+ Communication Interface Module
Series	PLC-5 / Legacy DH+
Form Factor	Half-size ISA 8-bit / 16-bit card
Network Protocol	Data Highway Plus (DH+)
Supported Systems	PLC-2, PLC-3, PLC-5
Data Rate	57.6 Kbaud (DH+ synchronous)
Async Baud Rate	9,600 / 19,200 baud
Connector Type	62-pin D-shell connector
Power Requirement	+5V DC @ 0.4A, ±12V DC @ 0.04A
Function	PC-to-PLC communication interface

Physical Dimensions & Weight

Item	Value
Size (L × W × H)	Approx. 263 × 58 × 28 mm
Weight	~0.4–4.3 kg (varies by revision/measurement source)

Recommended Related Models

1784-PKTX – PCI-based DH+ communication interface
1784-KTX – advanced DH+ PC communication card
1785-ENET – Ethernet communication module for PLC-5 systems
1756-EN2T – modern ControlLogix Ethernet module (replacement architecture)
1771-KE – legacy PLC-5 communication adapter

Popular Allen-Bradley Legacy Communication Models

1784-PKTX DH+/EtherNet communication card
1784-KT (this model) DH+ ISA interface module
1770-KF2 Data Highway communication interface
1756-EN2T EtherNet/IP communication module
1761-NET-ENI MicroLogix Ethernet interface

Applications

The 1784-KT is used in legacy industrial environments such as:

PLC-5 / PLC-3 programming and diagnostics
Data Highway Plus (DH+) network monitoring
Industrial workstation-to-PLC communication
SCADA systems in older automation plants
Factory retrofitting and legacy system maintenance
Engineering tool connectivity for vintage Rockwell platforms

It is especially valuable in brownfield facilities where upgrading the entire control system is not feasible.

Advantages

Direct PC access to DH+ industrial networks
Stable and deterministic legacy communication protocol
Supports multiple PLC generations (PLC-2/3/5)
Enables engineering and diagnostics from a workstation
Reliable operation in long-life industrial systems
Proven Rockwell Automation legacy ecosystem compatibility
Useful for plant modernization and migration projects
Strong durability for industrial computing environments

Technical FAQs

1. What is the 1784-KT used for?
It connects a PC to Allen-Bradley DH+ networks for PLC communication.

2. Is it a modern Ethernet device?
No, it uses the legacy DH+ protocol, not Ethernet/IP.

3. Which PLCs does it support?
PLC-2, PLC-3, and PLC-5 systems.

4. What type of card is it?
An ISA expansion card (8-bit/16-bit compatible).

5. Is it still in production?
No, it is a legacy/discontinued product.

6. What software works with it?
Older Rockwell tools such as 6200 software, INTERCHANGE, and legacy PLC programming suites.

7. What is DH+ speed?
Approximately 57.6 Kbaud synchronous communication.

8. Can it be used in modern PCs?
Not directly; modern systems lack ISA slots, requiring legacy hardware or emulation setups.

9. What replaces it today?
EtherNet/IP-based modules such as 1756-EN2T.

10. Why is it still relevant?
Many industrial plants still operate PLC-5 systems that rely on DH+ infrastructure.

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Allen Bradley PLC

Allen-Bradley 1784-KT Data Highway Plus (DH+) Communication Interface Module