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
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
Motor := 1; inside an IF with no ELSE is an OTL, and the Logix Structured Text manual’s own first example uses [:=] and a separate branch to avoid exactly that. Structured text for ladder people usually starts as a translation of a rung, and the rung’s OTE — which writes its bit false on … Read more
On an S7-1200 or an S7-1500 there are four places a function block can keep state that is not in its instance DB, and every one of them makes a second FB instance of FB_Valve share memory with the first. The report is always one of three: valve 2 opens when valve 1 is commanded, … Read more
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.
On a 1.5 m zone pitch at 0.28 m/s, a 600 mm carton is invisible to both photo-eyes for 3.2 seconds of its journey between them. An upstream zone whose release permissive is nothing more than “the next eye is clear” will use that window to send a second carton, and the two of them … Read more
Time it with a stopwatch before you type anything into the preset: the longest carton you run, crossing the photo-eye, on the slowest zone. A 1219 mm carton at 0.28 m/s sits on that eye for 4.35 seconds, which is why the 2000 ms that came across with the copied project trips every time the … 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
Zone 5 is stopped, PE5 is clear, Zone[5].Expecting is 0, and there is a 600 mm carton standing 30 mm short of the beam that no zone on the line is driving. Zone 4 behind it has a carton on its eye, Owns clear, its hold timer done, and every permissive it needs to release … Read more
The warehouse system’s report for the night shift said 4,629 cartons sorted, 100% to the lane the order wanted, and the lane 2 pallet had 19 cartons on it that belonged in lane 3 and a picker who found them at 06:40. The sorter had no way to know. Its scanner read the label, its … Read more
Zone 6’s eye came out of stores as a 42EF-P2KBB-F4, went onto the bracket in place of a 42EF-P2JBB-F4, and from the next 600 mm carton on, zone 6 reported occupied while it was empty and empty while a carton stood on it. One letter in the fifth position of the catalogue number, K for … Read more