How to avoid "bricking" Point I/O modules when you attempt to flash firmware

Failed to flash 1734-OE4C step 1I was recently contacted about some very experienced controls engineers who had ran into a strange issue. They had come across a firmware problem with one of Rockwell’s 1734 Point I/O modules, but weren’t having any luck successfully upgrading the firmware.

Actually, it was worse than that sounds. The bug the had been found in the middle of a very tight start-up schedule. And when the manufacturer found the bug six months earlier, it had not sent out proactive notices to the owners of the products.

The next day I visited the site to see if I could help. When I arrived and booted up my laptop, I started by launching Windows task manager and ending any processes and programs that I wouldn’t need running to flash firmware. Then I deleted all my RSLinx drivers and only added back in the one driver I would be using.

Failed to flash 1734-OE4C step 2Next I opened an RSWho window and browsed the 1734-AENT’s backplane to be sure RSLinx could see the I/O modules. Then I launched ControlFlash, crossed my fingers, and attempted to flash the first of several dozen 1734-OE4C modules.

Even with a quarter century of experience using PLC’s, I still got a little nervous as I watched the progress bar. The engineers that I had come to help had told me the firmware flash never got much past 10%.

Flashing of the first module was successful, but it was also a little bittersweet. While it did mean that the startup of Point I/O racks could continue, it didn’t explain why several of the engineering firm’s PC’s had failed to flash the same type of module?

I went ahead and flashed nearly a dozen modules before they were taken out to the field to be swapped out. As I waited more modules to flash, I thought it might be worth calling Rockwell’s Tech Support to see if there was an undocumented way of re-flashing the modules that had been bricked.

Failed to flash 1734-OE4C step 3While on the phone with Tech Support, I became a little distracted. After giving up on the failed units, I attempted to flash another new module, but surprisingly it failed. Stunned, I just sat their asking myself what I’d done differently? Why was my laptop now unable to flash these Point I/O modules? What had I missed?

I cycled power to everything and attempted to flash another module and had success, but then the next two I attempted failed. I began running through the procedure with one of the firm’s engineers when it hit me. In my attempts to reflash the old modules, and distracted while talking on the phone with Tech Support, I had stopped closing the RSWho window which was browsing the Point I/O backplane.

Now, I typically leave the RSWho windows in RSLinx open and browsing, as I often “alt-tab” back and forth between RSLinx and RSLogix. However, when I had initially began flashing the Point I/O modules earlier that morning, I had closed the RSWho just to be sure I had as few programs using the network as possible.

Failed to flash 1734-OE4C step 4Later, when I had gotten sloppy and left the RSWho window open and browsing the backplane, that small amount of additional network traffic had caused the failure of ControlFlash to successfully upgrade the firmware of the 1734-OE4C.

To confirm this was indeed the issue, we connected up one of the engineering firm’s PCs which had previously always failed to flash these modules. Then we attempted to flash several 1734-OE4C module, but this time with the RSWho window closed, and they were all flashed successfully.

So word of advice to anyone using Point I/O: If you plan to flash any of your Point I/O module’s firmware, play it safe and make sure you’ve closed the RSWho window inside of RSLink classic. Otherwise, you may find leaving it open will result in your module becoming a useless “brick.”

I hope this article about flashing Point I/O modules was helpful. If you have any comments, questions, or corrections please don’t hesitate to share them with us by using the “leave a reply” form at the bottom of this page.


Shawn Tierney
Automation Consultant
Insights In Automation

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