About 1794-ASB

The Allen-Bradley 1794-ASB is an old adapter module that is part of the flex I/O series. It supports 8 different modes of addressing, of which the main ones are complementary, complimentary 32, compact 32, and standard 32. Each mode allows the processor to receive different levels of information. This adapter works with a very low voltage, so a protected extra low voltage (PLEV) or a safety extra-low voltage (SELV) module should be used to power it. This unit requires an input voltage of up to 24 Volts DC nominal, where its input voltage rate goes from 19.2 to 31.2 Volts DC and it includes a 5% AC ripple. The communication rate supported by this product is 57.6kbps, 115.2kbps, and 230.4kbps. The 1794-ASB is equipped with 3 indicator lights which include green for an active adapter and red for a local fault as well as an adaptor fault. The flexbus output current is 640 mA at a maximum when the isolation voltage is 500 Volts AC between the user power and the flexbus. The maximum consumption of power is 450 mA from a constant 24 Volts DC power input. The maximum power dissipation by the Allen-Bradley 1794-ASB is 4.6 Watts at 31.2 Volts DC and the thermal dissipation is 15.7 BTU/hour at 31.2 Volts DC.

The 1794-ASB’s compact size makes it easy for the user to carry and use it. Its dimensions are approximately 4 x 2 x 4 inches and it weighs only 6 ounces. The Allen-Bradley 1794-ASB is an obsolete Adapter Module and is part of the FLEX I/O series. The 1794-ASB connects FLEX I/O modules to I/O scanner ports via a communication network. It has a built-in power supply which converts 24 Volts DC to 5 Volts DC for the backplane in order to power the FLEX I/O modules. The 1794-ASB adapter can also join an existing system or replace a previous unit. It also functions well with the Allen Bradley PLC 3 and 5 series. Additionally, the 1794-ASB can recognize the safe state data for the FLEX Integra analog modules, and it is capable of using thirty-two point FLEX I/O units. The user must use a 1794-ASB Series D or later module when utilizing the FLEX Integral analog modules in the configuration of your setup. This unit can communicate with the 1747-SN via Remote I/O communications and RSLogix 500 software.

FAQ for 1794-ASB

Question: How many I/O Modules can a 1794-ASB communicate with?

Answer: One 1794-ASB adapter can communicate with up to 8 FLEX I/O modules. This module powers the internal logic for up to 8 I-O Flex modules.

Question: What are the alternate series for the 1794-ASB module?

Answer: This module's alternate series include Series A, B, C, D, and Series E adapter modules.

Question: What is the 1794-ASB communication rate?

Answer: The 1794-ASB communication rates are 57.6 Kbps, 115.2 Kbps, and 230.4 Kbps.

Question: Can this module be purchased with a warranty?

Answer: Yes, the 1794-ASB comes with a free one-year warranty from DO Supply, Inc.

Question: Does the 1794-ASB carry any indicators?

Answer: Yes, this module contains a number of Diagnostic Status indicators.

Question: Where can I send the 1794-ASB to be repaired?

Answer: DO Supply, Inc. offers a variety of repair services for the 1794-ASB.

Troubleshooting for 1794-ASB

The 1794-ASB remote I/O adapter/power supply is a Flex I/O module that is used to communicate between connected SLC or PLC racks across an RIO Link.
The 1794-ASB communicates with PLC, SLC, and ControlLogix models, using baud rates of 57.6k bits/s, 115.2k bits/s or 230.4k bits/s

Note: Three conditions can cause the remote I/O adapter to produce a communication fault.

• no remote I/O communication for more than 100ms 

• no command issued to this address over the remote I/O link within the last 255 link transactions 

• communication is lost when the Rack Fault Select is enabled

1794-ASB Troubleshooting

• Check dip switch settings 

• Ensure connecting pins are straight and aligned properly 

• Check settings on devices communicating directly to the 1794-ASB

• Make sure the Baud rate is set correctly on all devices 

• Check communications cable and resistors for damage 

• Be sure that Line 1, Shield, Line 2 are correctly placed on the devices being used 

• Use the reset button to reset the module and resume communications on both modules when a communication error occurs

• Check publication for additional information and configuration settings

Testing 1794-ASB 

In this example we configure our G-data to ¼ rack before downloading.

The following parts will be used :

• 1747-L553

• 1747-SN

• 1746-A7

• 1794-TB3

• 1794-OA8

• Configure communications device 

• Connect RIO cable 

• Apply power 

(This is with the ASD module on with no communications)

• Download program to the 1747-L553 

• Active light will illuminate, letting us know we have communications 

• Turn on the outputs through the output table 

• If actuated lights turn on, the 1794-ASB is working properly 

Repair Services for 1794-ASB

Type	Lead Time	Price	Action
Repair Service	2-4 weeks	Ask	Get Quote

Our highly skilled technicians can repair your 1794-ASB. All of our repairs come with a 1 Year DO Supply Warranty. Please contact us for additional information about our repair process.

Revisions for 1794-ASB

Please refer to the manual for more information about the 1794-ASB such as the wiring diagrams, data sheets, firmware information and migration or obsolescence details.