Since that download the CPU ERROR LED flashes and slot 3 sits there faulted in the online view. Slots 2 and 4 are green and their channels are live, so it is one module and not the rack. Diagnostics says "The module is not configured as set", or near enough, I will get the exact line tomorrow.

Power cycled the CPU twice and loaded the hardware configuration again on its own, no change. Slot 3 is the DI DQ card that runs the two duty pumps, so nothing starts while it is out.

Is a flashing ERROR and one module down a sign the card has failed, or does a download do something to a module that a power cycle won't undo?

The dialog says "This object was not found." and down in the bottom corner of it, small, there is "256:31". That's the whole message, no block number, no address, nothing else.

I closed SIMATIC Manager and reopened it, restarted the PC, and copied the project to another machine and tried there. Same dialog every time. I've been searching for two days and I'm stuck. Every S7 error code list I find is OB numbers and CPU LED patterns, and not one of them has anything that looks like 256:31 in it.

Does that number mean anything to anyone, or is it one Siemens never wrote down?

Since my change the CPU goes to STOP after some minutes, SF LED on. Buffer says:

"STOP caused by programming error (OB not loaded or cannot be loaded)"
"OB 121 not available"
"Area length error when writing. DB 10, byte address 2048"

My FC uses SFC20 BLKMOV with an ANY pointer that I build from a counter, copied off a forum post. I did a memory reset and loaded everything again and it runs for a while and then stops again. The battery in the CPU is old, might be that? Or is it that ANY pointer, I'm not sure I understand what I copied.

The diagnostics buffer has the same entry hundreds of times:

"Area length error when reading. Global DB, DB number 120, byte address 4000. Block FC 45. Programming error."

Words may be slightly off, I'm reading it off a photo. I went online and did a STOP and RUN, the LED goes off and comes straight back, and a power cycle does the same. The site electrician says the CPU is faulty and wants to order one, and I can't explain the LED well enough to talk him out of it.

Is there a way to clear it without stopping the machine? Could someone explain what DB120 byte 4000 is telling me, so I've got something to say to him?

Setpoint 8.0 C. When the tank drops to 6.0 C the output goes to 100 percent and the chilled valve opens wide, so it gets colder still, and with a warm tank the output sits at 0. Exactly backwards. I put a negative Gain in the tuning parameters and the block did nothing useful with it, and the transmitter checks out against a thermometer. Someone here told me to swap the transmitter wires to flip it, and I'd rather not wire a lie into the panel.

Not sure the block even has a direction setting. What's the right way to do a cooling loop on it? Could someone explain how PID_Compact is meant to be told it's cooling, without me wiring a lie into the panel?

Turn the shaft by hand and the count is right, 400 per turn. Run the motor and it counts about half what it should over ten seconds. Not noise, pulses are simply missing. I tried 1x instead of 4x and swapped A and B, same ratio missing, and the scope on I0.0 shows a clean 24V square, 250 us high, 250 us low.

Why does it count right slowly and wrong fast? The datasheet says HSC1 goes to 100 kHz and I'm nowhere near that. So is something eating the pulses before the counter ever sees them, I guess something I've not set on the input?

In the control panel I pick "PLCSIM Virtual Eth. Adapter", start the instance, give it 192.168.0.1, and it goes green, RUN. In TIA I do Go online with the PG/PC interface on my laptop's Intel Ethernet, Start search, and the list stays empty every time. I turned the Windows firewall off, reinstalled PLCSIM Advanced and restarted everything twice.

Ok so is the instance not really on the network, or is TIA looking in the wrong place? I think I'm pointing TIA at the wrong adapter, but I don't want to guess my way down that dropdown.

Every tag comes up Bad quality, 30 of them, all in DB1. The same server and the same driver read a 315-2 PN/DP on line 1 without a problem. The event log says "Device 'Line2.Filler' read request failed, block DB1", roughly. Ping's fine, I rebooted the server box and rebuilt the device with rack 0 slot 1 and then rack 0 slot 0, no change, and DB1 isn't optimized, I checked the block properties.

What's different about the 1200 that the 300 doesn't care about? Pretty sure it's something on the CPU side and not the server, because the 315 reads all day off the same box.

"CPU goes to STOP mode. Cause: maximum cycle time exceeded twice in one cycle"
"Time error. Maximum cycle time exceeded. OB 80"
"Time error. Maximum cycle time exceeded. OB 80"

The new FC runs a FOR loop over 4000 recipe entries every scan, in OB1 with the rest of the recipe code. I raised the max cycle time from the default 150 ms to 300 and it still stops, just less often. The customer wants 6000 ms so it never stops, which I'm not doing.

Is the FC really that slow, or is the HMI loading the CPU? They added a second panel around then and I'm out of ideas past that. Is 4000 entries a scan too much for OB1, or am I missing something about the panel?

From the PLC I write control word 16#047F and speed setpoint 16#2000 into the telegram with DPWR_DAT. The status word comes back, r0052 in Startdrive shows bit 0, ready to switch on, and that's where it sits. Motor never turns, no fault, no alarm. I re-assigned the device name from scratch and checked p0840 is r2090.0 so the ON command comes off the telegram.

In Logix I'd set the Start bit and go. What does the G120 want that I'm not giving it? Any pointers welcome.