We run a shift report in Excel that pulls about a dozen tags off a 1769-L33ER through RSLinx Classic DDE. Yesterday the sheet sat on the same twelve numbers from 06:00 through to 14:00 and nobody spotted it until the counts came out identical to the shift before.
The topic in RSLinx still says good, no error in any cell, the values are just the ones from first thing in the morning. I closed Excel and opened it again and everything jumped to current, then a couple of hours later it was stuck at the new numbers instead.
I've already swapped the topic for a fresh one on the same path and got exactly the same behaviour, so I'm not sure whether that's the link letting go quietly or the sheet not asking anymore.
Which machine is the sheet actually open on, and is that workbook the original or a copy somebody dragged onto the share. Before anything else, open it and tell me what Formulas, Calculation Options says.
> the link letting go quietly
It does that. I've had Classic drop a topic after a Windows update restarted the service and the cells keep the last value with no error at all, which is the part that gets you. Open DDE/OPC Topic Configuration and see whether it still shows one client and whether the counters are moving. If I remember right the counters sit still once the topic is dead.
Counters are moving and it says one client, so RSLinx is fine, its doing what it should.
Calculation says Manual. I didn't set that. And there are two copies of the workbook, the live one on the line PC and one our quality lad made on the share last week.
There it is. Calculation mode is not a property of the workbook you are looking at, it belongs to the Excel instance, and the instance takes it from whichever file opened first. Your quality lad saved his copy with Manual on. Somebody double clicks that one in the morning, the live sheet opens in the same instance afterwards and it is Manual too. DDE pushes the new value into the cell, nothing recalculates, and the sheet sits there looking perfectly healthy. Press F9 and I reckon the lot will jump at once.
F9 and all twelve moved. Right.
Then fix his copy, not yours. Open it, set Automatic, save, and get it out of the root of the share into somewhere nobody opens by accident. Worth knowing how the link is put together underneath if you ever rebuild it, there's a writeup on this here: https://plctr.com/how-to-get-data-from-plc-to-excel/
Sorted. The copy on the share was saved with calculation set to Manual, and because that one gets opened first every morning it put the whole Excel instance into Manual, live sheet included. Set the copy back to Automatic, moved it two folders down out of the way, and the live sheet now opens from its own shortcut so it never shares an instance with anything.
What I still cannot explain is why it ran a couple of hours before sticking rather than going stale straight away. Thanks suel, jcasey and rsdave, I would have been staring at RSLinx all week.
Marking solved. Good one for anyone whose numbers look healthy and are not.
plctr.com team