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
A PowerMonitor 1000 puts L1 current in input registers 30201 and 30202, as one IEEE 754 float with the high word in 30201, and answers function code 04 for it. Those four facts — which register, how many, which order, which function code — are the whole job of getting a Modbus RTU power meter … Read more
An optimized block on an S7-1500, or on an S7-1200 at V4.x, is created with a 100 byte memory reserve, which is room for 25 Reals of new Statics before a download in RUN has to reinitialise the instance DB. Whether an S7-1500 interface change makes the load preview put “reinitialize” against the block is … 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
Produced and consumed tags stop at 500 bytes, and at 480 once the data crosses a network, because the transfer spends 20 of them on overhead. Try to produce an INT array and Logix Designer refuses: DINT, UDINT, LINT, ULINT, REAL and LREAL are the atomic types that go across on their own, and anything … Read more
An S7-1500 area length error leaves the CPU in RUN with the ERROR LED on. Read the buffer entry, find the index that runs past the array, fix the order.
PLC building automation that a stranger can maintain: naming, sequences of operation in the code, staging, BACnet mapping, trends, alarms and overrides.
An eight-station rotary indexer on a 5069-L330ER. An SQO drives the station outputs, and on the first false-to-true transition the outputs light station one. Not station zero. Station zero never fires at all, and the operator wants to know why the first pot off the carousel is empty. That is not a bug in your … Read more
We can use the “FOR DO” command structure to find the sought value in an array. In the example below, I will explain how to run the “FOR DO” command in the STL language that I have prepared for you and understand the index number of a number in the array or whether this number … Read more
We all know what the mean command means and what it does mathematically. The average command is generally used to average a series of variables. In general, we assign the data to an array every second so that it is not affected by instantaneous changes at the decision-making point according to variable values such as … Read more
In this topic, we will see how the FFL (Fifo Load) command works and we will examine the Fifo command. The FIFO command is a command used in arrays. As the name suggests, it works with First In First Out logic. Also because arrays are used as local databases in PLC. With the FIFO command, … Read more
Check for a Specific Fault In this article, we will learn how to clear fault on Allen Bradley PLCs. Which is the continuation of our previous article. We will examine the automatic cleaning of the fault types that we have determined specifically, and error notifications at prescan time. You can find our previous article at … Read more