Logix Designer, RSLogix 500/5000, RSLinx, FactoryTalk and the faults you meet on a ControlLogix or CompactLogix line.
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
Two cartons released 1.1 seconds apart from line A and line B arrive at a 30 degree merge at the same moment, because line A’s release eye is 1.3 m from the junction and line B’s is 1.7 m, and 0.4 m at 0.28 m/s is 1.4 seconds. The rung that let that happen was … Read more
A 42EF retroreflective eye bolted 150 mm back from the discharge roller of a 1.5 m zone stops a 600 mm carton with 750 mm of zone still behind it, and stops a 1219 mm carton with 131 mm. Move the same eye to 50 mm from the discharge and the first carton overshoots into … 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 one button start and a one button stop written as separate rungs both end in OTE Motor, and the second one wins every scan, which is why the panel lamp flickers at scan rate and the contactor never pulls in. Two things fix it: an ONS or OSR so the press lasts one scan, … Read more
A 1734-AENT on a remote I/O rack stores its chassis size in non-volatile memory, and the user manual says in as many words that the chassis size setting is not communicated to the adapter during a connection request from the controller. Download a project with the new rack in it and the adapter you just … Read more
A spare CPU firmware mismatch looks like this: a new 1756-L83E ships at firmware revision 1.xxx, and a project saved from Logix Designer v33 will not download to it until the controller is at some 33.xxx. Those two facts sit on the same page of the ControlLogix 5580 user manual, and between them they are … 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
Siemens gives you a Retain checkbox and a published memory budget. Rockwell gives you neither. Here is what each one really keeps, and how to check it.
A 1769-IQ16 takes 8 ms to see an input. Here is the counter module that will not, the quadrature arithmetic, and where the pulses actually get lost.
Read process gain, dead time and time constant off one bump test, then enter them in the units PIDE actually wants instead of the ones the PID wants.
Pick between TON, TOF and RTO, find out what retentive actually covers on each platform, and stop losing an afternoon to a timer that never times out.