Written by Miya Zheng, Director at Moore Automated

Miya Zheng serves as Sales Director at Moore Automated and has over 12 years of practical experience in the automation industry. Over the years, she has built a solid understanding of automation technologies, market trends, and customer needs across different sectors.

She has been actively involved in developing long-term client relationships, leading sales initiatives, and contributing to business growth in both established and emerging markets. Her experience combines hands-on industry insight with a consistent track record of delivering results.

Introduction

If you frequently work with older Allen-Bradley control cabinets, you may have encountered the Allen-Bradley 1794-OM8 module. While it is not a new product, that is precisely why it remains a point of interest for maintenance teams today.

The 1794-OM8 is an 8-point AC digital output module belonging to the Allen-Bradley FLEX I/O series. Designed for 220/240V AC applications, it provides eight non-isolated outputs. Rockwell Automation has currently designated this product as "End of Life" and announced that it will be officially discontinued on October 31, 2026, with no official replacement product currently planned by Rockwell.

That matters when a plant is still running a FLEX I/O system. Replacing one failed module is often much easier than redesigning an entire I/O section.

What Does the Allen Bradley 1794-OM8 Actually Do?

The basic job is simple. The PLC sends an output command, and the 1794-OM8 switches the connected AC load.

The module has 8 outputs, with a nominal output voltage of 240V AC. Its specified output range is 159–264V AC at 47–63 Hz. Each output is rated up to 500 mA at 55°C, and the total module current rating is 4.0 A, based on eight outputs at 500 mA.

There are a few numbers worth remembering when checking a replacement:

l  8 non-isolated outputs

l  159–264V AC output range

l  240V AC nominal

l  500 mA maximum per output at 55°C

l  4.0 A maximum module current

l  2.5 mA maximum off-state leakage

l  1.5V AC maximum on-state voltage drop at 0.5 A

l  7 A surge current for 40 ms, repeatable every 8 seconds

l  1/2 cycle maximum signal delay for both OFF-to-ON and ON-to-OFF

l  60 mA maximum FLEXBus current at 5V DC

l  5.0 W maximum power dissipation at 0.5 A

These specifications are more useful than they may look on a catalog page. For example, the 500 mA figure is a per-output limit at 55°C, while 4.0 A is the module-level limit. They should not be treated as two separate ways of increasing the same load capacity.

The 1794-OM8 also has eight yellow status indicators, which give technicians a quick field-side indication of the output states.

Why Maintenance Teams Still Look for the 1794-OM8

Here is the practical side.

Imagine a machine has been running for years with FLEX I/O. The wiring is already in place. The terminal bases are already installed. The PLC program is already configured. Then one output module fails.

The problem is no longer “Which new I/O platform should we buy?” The problem is much smaller: Where can we find the correct 1794-OM8?

The module is associated with terminal bases including the 1794-TBN, 1794-TBNF, 1794-TBNK and 1794-TBNFK. The installation documentation also notes that the module outputs themselves are not fused and recommends output fusing; when using the 1794-TBNF, a 0.8 A, 250V slow-blow fuse is specified for the output protection arrangement.

Another useful number is its physical size: approximately 94 × 94 × 91 mm. The specified operating temperature on Rockwell's current product page is 0…55°C.

The module also supports the FLEX I/O architecture's Removal and Insertion Under Power (RIUP) capability when the system and installation conditions permit it. That can be useful during maintenance because a technician may be able to replace an I/O module without shutting down the entire control system. Proper site procedures and electrical safety requirements still come first.

For companies maintaining older equipment, this is where sourcing becomes important. A failed module does not necessarily mean the whole control cabinet needs to be modernized.

That is why searches for Allen Bradley automation parts often include older FLEX I/O numbers. And when a particular catalog number is no longer in normal production, it can quickly become one of those hard-to-find automation parts that maintenance departments want to keep on hand.

Conclusion

The Allen Bradley 1794-OM8 is a fairly straightforward module: eight AC outputs, 240V AC nominal operation, 500 mA per output at 55°C, and a 4.0 A module rating.

But the details matter. The outputs are non-isolated, the voltage range is 159–264V AC, the maximum off-state leakage is 2.5 mA, and the output response is limited to a maximum of half an AC cycle. Those are the numbers worth checking before ordering a replacement.

With Rockwell listing the 1794-OM8 as End of Life and no planned replacement, finding the exact part can become increasingly important for plants that want to keep existing FLEX I/O systems running.

For maintenance teams looking for Allen Bradley 1794-OM8, Allen Bradley automation parts, or other hard-to-find automation parts, the old rule still works: check the full catalog number, check the electrical ratings, check the terminal base, and then source the exact module you actually need.

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FAQ

Q1. How does Moore Automated approach verification of a hard-to-source 1794-OM8?
Moore Automated states that it can verify the complete part number, provide product and packaging photos when available, and confirm condition, warranty, lead time and commercial terms in writing.

Q2. What should buyers provide when requesting a quotation for the Allen Bradley 1794-OM8?
The most useful details are the complete catalog number, required quantity, required condition and destination country. Moore Automated also recommends providing a clear nameplate photo when the exact model is uncertain.

Q3. Why is the 1794-OM8 becoming a more important sourcing item for legacy FLEX I/O systems?
Rockwell currently identifies the 1794-OM8 as End of Life, with discontinuation scheduled for October 31, 2026 and no planned Rockwell replacement. This makes exact-model sourcing increasingly relevant for existing installations.

Q4. Which technical details should be cross-checked before purchasing a replacement 1794-OM8?
Check the complete catalog number, 8-point configuration, 240V AC nominal rating, 159–264V AC operating range, 500 mA per-output rating, 4.0 A module rating, non-isolated architecture and compatible terminal base.

Q5. Can the 1794-OM8 still be relevant even though it has reached End of Life status?
Yes. End of Life describes the manufacturer's lifecycle status; it does not automatically mean that every installed 1794-OM8 system must be replaced immediately. Existing FLEX I/O installations may still require exact spare modules for maintenance and repair.

If you have any inquiry,welcome to contact Miya [ Mobile : +86-18020776792  , Email : miya@mvme.cn ]

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