Unicast or Multicast on an EtherNet/IP I/O Connection: the Checkbox and What It Decides

Two drawings of the same drop: on the left, unicast, where a 1756-EN2T owner at 192.168.1.10 receives one stream from a 1734-AENTR at 192.168.1.50 and a second controller at 192.168.1.11 receives nothing, its listen-only connection rejected with 16#0106; on the right, multicast, where the adapter sends one stream to a group address and the switch delivers it to both controllers, with the owner and the listen-only connection both marked multicast

Unicast or Multicast on an EtherNet/IP I/O Connection: the Checkbox and What It Decides Module fault 16#0106 appeared on the second controller’s listen-only copy of a 1734-AENTR drop, and the string underneath it reads “Module owned and configured by another controller. Module may accept only one connection if Unicast is used.” The owning controller had … Read more

Catching a PLC Intermittent Fault with a Trend in the Controller: the Tags, the Rate, and the Latch That Keeps the Data

Eight tags in the PLC intermittent fault trend with where each comes from, how often it can change, and why it is in

Line 2’s palletiser infeed stops about once a shift with Infeed_Jam latched, the alarm log says “Infeed jam” with a time, and the 1756-L83E, the PowerFlex 525 and the 1756-IB16 feeding the discharge photo-eye all check out every time somebody looks. Whatever happens takes a few tens of milliseconds and happens hours apart, and the … Read more

Cross-Fault Detection Between Two Safety Channels: What a Short Between the Wires Looks Like to the Controller

plc programming cross fault detection two safety channels 1 plc

Inputs I0 and I1 on a 1791ES-IB8XOBV4 went solid red one afternoon with the guard closed, and the DCS instruction in the GuardLogix 5580 behind them has held Input Status false ever since. The guard switch on the infeed has two NC contacts in one four-core cable, the cable was crushed where it enters the … Read more

Powering a Raspberry Pi from Panel 24 VDC: The 1606 Supply, the Ride-Through and the Shutdown Signal

The DIN rail left to right: the 1606-XLE240E with DC-OK on 13/14, the 1606-XLSBUFFER24 on the same bus, a 2 A branch fuse, the 24 V to 5.1 V converter, and the Pi with GPIO17 fed from the contact

A 1606-XLE240E Series B has a DC-OK relay on terminals 13 and 14 that closes while the 24 V bus is above 90 % of its set point, and a Raspberry Pi 4 needs 5.1 V and somewhere between five and twenty seconds of notice to halt without corrupting its card. Raspberry Pi panel power … Read more

Reading a Logix Tag into Node-RED on a Raspberry Pi Without Writing Code

plc programming logix tag node red raspberry pi no code 1 plc

A Node-RED Logix tag read takes one install script, one palette install and two dialogs on a Raspberry Pi 4: Zone7_Speed from a 5069-L306ER appears in the debug sidebar as 30.0, and none of it involves typing a line of code. The node that does it is node-red-contrib-cip-ethernet-ip 1.1.3, installed from the palette manager, configured … Read more

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