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We’ve gotten feedback from several people who have asked what I carry around to deal with serial or Ethernet communications issues. So I dumped out my comm tool bag and here’s the list of all the stuff.
Earlier this week, I was working with one of our Honeywell Trendview X-series paperless recorders. The X-Series is capable of accepting data input from a USB barcode scanner — typically used for batch identification or for user name logins — but mine wasn’t working right.
When I tried to scan a barcode, I got an error message, and it stumped me. Luckily, I figured it out in a few minutes.
We keep a Honeywell XYR6000 field transmitter network setup at the Lesman offices for training, customer demonstrations, and site surveys. And part of my job is to keep the system in working order.
Honeywell releases incremental firmware updates when they need to fix a bug or add functionality to the systems. I’d downloaded both the 201.1 and 202.1 update files from the Honeywell website, but had procrastinated in doing the installation. (Never happens to you, right?)
When I got around to doing the updates today, I pulled out the wireless device manager (WDM) manual [1.8MB PDF]. and turned to section 6.2, page 131. It has about 10 pages of step-by-step instructions on the update/upgrade process.
But then, I found myself wishing for another of those “missing pages from the manual”. While it has all the steps, here’s what’s missing: A map that tells me how long the steps take.
This one qualifies as a “Page the manufacturer left out of the manual”, and was brought to my attention by a customer who was having problems with remote reset on his flame safeguard system.
A typical multi-burner furnace has Honeywell 7800 flame safety controls on each burner as shown below. Modbus is used to fetch fault codes for the plant’s HMI system, and to allow the control system to remotely reset the flame safety controls.
The reported problem was that Modbus did everything as advertised except remote reset on the one control that had a S7800A keyboard display module attached (colored orange in the network image on the right, or as shown in the controller image below).
That unit would only do a reset when an operator pressed the reset button on the RM7838C controller. Modbus failed to get the controller to execute a remote reset.
The problem wasn’t communications – all Modbus read functions worked and Modbus writes to all the other controls worked as expected. But somehow, the write command to do a reset action was ignored by the S7800 keyboard display.
So, what’s causing the problem?