Bridge the Allen-Bradley Bulletin 1771 I/O system to new 1756 I/O modules with the Bulletin 1492 I/O wiring conversion system from Rockwell Automation.

Jeff Kilburn

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I/O wiring can be among the most challenging (and perhaps feared) of upgrades. When replacing input/output connections, questions to ask include:

• Is there documentation for all of the I/O wiring?
• How much time is required?
• If a wiring error is made during the upgrade, do I have the time and the proper personnel to troubleshoot the system?
• What if the devices are not working as expected after the upgrade—can I continue to use the old I/O for a while?

I/O replacement represents a large investment and the potential risk of extended downtime. Rockwell Automation provides an upgrade for Bulletin 1771 I/O that can accommodate existing schedules and budgets while helping to minimize the risk of errors that could result in extended downtime.

Bulletin 1492 I/O wiring conversion system provides a method to reconnect the existing 1771 I/O wiring to Rockwell Automation new 1756 I/O modules without disturbing the field wiring connections. This can help dramatically reduce labor and downtime that could result from wiring mistakes. Planning a migration is more manageable as I/O can be swapped one rack at a time or all at once, based on the schedule and budget. In either case, old and new I/O networks can run simultaneously. I/O cross-reference documentation helps assure accuracy and provides historical backup for future troubleshooting or diagnostics.

Additionally, the wiring conversion system provides a mounting assembly that helps reduce the need to drill new holes in the control panel to mount the new I/O chassis. This can help lower engineering costs and installation labor, but more importantly eliminate the metal filings from drilling new holes that can wreak havoc with the other electrical components in your panel. This mounting assembly uses the same panel footprint (length and width) as the 1771 I/O chassis. The new assembly with the 1756 I/O chassis is 10 in. deep; the 1771 chassis depth is 8.5 in. deep.

The speed and ease of the conversion provides some added benefits. A recent time study indicates that an 8-slot chassis can be converted in just over 6 minutes using the 1492 I/O wiring conversion system, while it takes almost 2.5 hours using the conventional method. The design makes it possible to quickly “undo” the I/O upgrade if you find your control system is not performing as required and further programming changes are required.

- Jeff Kilburn is global product manager, logic components, Rockwell Automation. Edited by Mark T. Hoske, CFE Media, Control Engineering, www.controleng.com.

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