Studio 5000

Kepware with a ControlLogix: the Tag Import, the Arrays, and What Breaks

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Five boxes in a row from Studio 5000 through the import route, the server group and the server tag to the client item, with four numbered red points marking where each join fails

Automatic tag generation against one 1756-L83E produced 5537 server tags in about ninety seconds, and the clients on that site reference 684 of them. The other 4853 are array elements nobody reads, structure members nobody reads, and a full PID_ENHANCED nobody has looked at since commissioning. They cost project load time, they cost browse time … Read more

JSR, SBR and RET: Passing Parameters Into a Routine Without a Controller Tag

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A diagram of one JSR call: the calling routine's program-scoped tags on the left, the JSR instruction with two input parameters and one return parameter in the middle, the subroutine's own program-scoped tags on the right, and a numbered list of the five steps from rung true to RET copying the answer back

JSR, SBR and RET: Passing Parameters Into a Routine Without a Controller Tag Type 4, Code 31 on a 1756-L83E, and the routine it pointed at was three rungs long. The general instructions reference gives three separate ways to earn that code and every one of them is about counting: a JSR with fewer input … Read more

The MSG Control Tag on a Logix Controller: What Each Tab Writes Into It

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Three columns headed Configuration, Communication and Tag, each listing the fields on that tab of the Message Configuration dialog next to the MESSAGE structure member the field is stored in, with a note that configuring the message once configures every rung naming the same tag

The MSG Control Tag on a Logix Controller: What Each Tab Writes Into It Line_Msg.DN came true on rung 13 of a 1756-L71 and the forty DINTs the rung was guarding still held last shift’s numbers. The bit had been set by a different message — a four-element write to a capper down on rung … Read more

The First Scan Bit in Studio 5000: What S:FS Is For, and What It Must Never Do

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Three stages across one transition to Run mode: prescan with outputs cleared, timers reset and inputs not current; the first normal scan with S:FS true for that one scan; and every later scan with S:FS false, annotated with what each stage resets

The bagger came back with 0.0 in every recipe setpoint at 06:10, with nobody at the HMI and no download on the log. The only change on that shift was a program that had been inhibited while somebody edited it and then put back in, and the initialisation rung inside it — one XIC on … Read more

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

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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

Firmware Mismatch on a Spare CPU: What Actually Has to Match

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plc programming spare cpu firmware mismatch 1 plc

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

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