Going Online on an S7-1500: Monitoring a Block, a Watch Table, and Values That Will Not Update
Monitor a block on an S7-1500, build a watch table, and work out why a value sits there: modify against force, optimised blocks, and what STOP does.
PLC
The First Download to an S7-1200: PG/PC Interface, the Subnet, and Why No Accessible Devices Appear
Start search comes back empty on an S7-1200. Work through the PG/PC interface, the subnet, the flash-LED check and a CPU that loads but stays in STOP.
Adding an S7-1214C to a New TIA Portal Project: Order Number, Firmware and Device Name
Get a CPU 1214C into an empty TIA Portal project: read the order number off the front, pick the firmware the bench CPU can take, and set the device name.
A MSG Instruction That Actually Works: Path, Type and the Error Codes
16#0204 appears twice in the same Rockwell reference manual with two different meanings, and which of the MSG instruction error codes tables you are reading decides where you spend the next hour. In the extended error codes for error 0001 it is Unconnected message timeout. In the module fault codes it is Connection Request Error: … Read more
Two PLCs, One Tag: Produced and Consumed Tags on ControlLogix
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
Sinking or Sourcing: Matching a PNP Sensor to the Input Card You Have
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
Reading a 4-20 mA Transmitter into a 1756-IF8: Wiring, Range and the Raw Value
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
PowerFlex 525 F059 Safety Open: Reading S1, S2 and the Protective Jumper
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.
Adding a Generic EtherNet/IP Module to the Ethernet Card: Connection Parameters and RPI
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.
Sizing a Year of Tag History on a Raspberry Pi: Sample Rate, Deadband and the Disk Arithmetic
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
Configuring an ET 200SP F-DI in TIA Portal: 1oo2 Evaluation, Discrepancy and the F-Destination Address
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
Docker on a Plant-Floor Raspberry Pi: Restart Policy, Log Rotation and the Container That Filled the Card
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
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