Every PLC and HMI tutorial on plctr.com: project setup, ladder and structured text, communication, troubleshooting and commissioning, written from the plant floor.
Produced and consumed tags stop at 500 bytes, and at 480 once the data crosses a network, because the transfer spends 20 of them on overhead. Try to produce an INT array and Logix Designer refuses: DINT, UDINT, LINT, ULINT, REAL and LREAL are the atomic types that go across on their own, and anything … Read more
PNP sensor wiring is decided on the input card’s spec sheet, and almost nobody reads that row. Under Voltage category, a 1756-IB16 says 12/24V DC sink and a 1756-IV16 says 12/24V DC source — same form factor, same 16 points, same 5V off-state threshold, and only one of them will ever see a PNP sensor … Read more
A 1756-IF8 analog input in integer mode lands on roughly -20,030 counts at 4 mA and 30,920 at 20 mA, which are not numbers anybody memorises. If the value in front of you is 3277, the card in the rack is a 1769-IF4 or 1769-IF8 running the Scaled-for-PID data format, and none of the 1756 … Read more
F059 Safety Open means both PowerFlex 525 safety inputs are unpowered. Read S1, S2 and S+, tell F059 from F111, and know when the jumper must come out.
Assembly instances, sizes, Comm Format and RPI for a device with no catalogue profile and no EDS file, plus the connection error codes that follow.
200 tags at one row a second is 17.28 million rows a day, and at the 47 bytes a row that SQLite measured on this machine for a typed, indexed table, that is 814 MB a day and a 32 GB card full in 32 days. The same 200 tags logged on change, with a … Read more
The station is an IM 155-6 PN with an ET 200SP F-DI 8x24VDC HF in slot 3, the CPU is a 1515F-2 PN on TIA Portal V17, and the hardware compiles clean with a warning that says the F-module has no valid PROFIsafe address yet. The guard door on channel 2 is wired as two … Read more
A Docker Raspberry Pi that stopped logging on a Sunday had /var/lib/docker/containers/3f9a…/3f9a…-json.log at 22 GB when du got to it, and the file belongs to a container whose only job was to reconnect to a broker that had been down since Thursday. Docker’s default log driver is json-file, its default max-size is unlimited, and a … Read more
A CPU 1515F-2 PN on TIA Portal V17, an ET 200SP station with an F-DI 8x24VDC HF, and channel 2 on it is a guard door. The buffer showed “Channel 2: Short-circuit” last week and the channel passivated; the electrician found a chafed wire in the door loom and repaired it, the buffer now says … Read more
A pycomm3 write of 95.0 to Line4_SP on a CompactLogix comes back to the Raspberry Pi with no error, and the line is now running at 95 % because nothing between the driver and the tag asked whether it should. A read-only logger becomes a control path the first time somebody puts a slider on … Read more
The 1791ES-IB8XOBV4 on the palletiser cell failed on a Sunday, the spare from stores has the same catalogue number and the same three address switches set to 21, and the yellow triangle over it in the I/O tree has not moved in forty minutes. The GuardLogix 5580 project has a safety signature, the module’s Safety … Read more
A 300 mm tote leaving zone 12 at 0.280 m/s onto a metering belt running 0.513 m/s arrives at the scanner 250 mm behind the tote that left in front of it, and a 600 mm carton on the same two belts arrives 499 mm behind its neighbour. Neither number has a timer in it: … Read more