BadIdentityTokenRejected is the answer an OPC UA server gives when the secure channel is up, the client certificate is trusted, and the session request arrives with no user in it, and on an S7-1500 with guest authentication off that is exactly where a first Python OPC UA client stops. It is the third of four … Read more
A pusher divert with its trigger eye 1.20 m upstream and a 2780 ms delay in the program was diverting 97% of the 600 mm cartons and 61% of the 300 mm totes, and every tote it missed was hit on its back corner and spun onto the takeaway sideways. The 2780 ms was right … Read more
A 1756-OF8 is a 0…20 mA module, and at full counts it puts out 21.29 mA. Nothing in the hardware knows that the positioner on the end of the wire wants 4 mA for closed and 20 mA for open, or that 0 mA on an air-to-open valve is the same as closed and 21 … Read more
A UDT holding a STRING, eight REALs, four DINTs and four BOOLs is 140 bytes, and the Data Type Editor in Studio 5000 prints that number under Data Type Size before you have written a rung. Fifty of them in a PLC recipe UDT array is 7000 bytes and one base tag, and that last … 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
PLC programming for beginners without the theory dump: pick a simulator, write a start/stop rung, add a timer and a counter, wire one HMI button.
Add one Static to an FB and every setpoint in the instance DB goes to zero. How the memory reserve prevents it, how to size it, and how to recover.
PLC networking done properly: switch features that matter, an address plan, VLANs, DLR rings with 1783-ETAP, PROFINET RT and IRT, NAT and port numbers.
How a PLC state model feeds OEE, downtime reason codes and SPC triggers on a rotary filler: the ST block, the tag structure and the classic mistakes.
Build a Logix Emulate chassis, run PLCSIM Advanced, test the HMI offline, and learn which parts of a machine you can trust a simulation to prove.
Remote access to a PLC that security will sign off: outbound VPN routers, read-only web HMI, an access rights table, a permissive rung and an audit trail.
From a blank FactoryTalk View ME application to a running PanelView Plus screen: shortcuts, tag syntax, a momentary push button and the MER transfer.