controllogix plc's programming guides


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jason s

i am programming a controllogix plc for the first time and was after any information regarding suggested guidelines and any help in general. this plc will also communicate to a citect pc and i was wondering if there is a way of minimising the plc memory scanned, something akin to placing all the scada information in one data file with the slc or plc5.

Chris Cooper

When programming the Control Logix try to keep all of your HMI data in arrays or double integer words. The Control Logix processor is 32-bit based - meaning that all the base data types will take up 32 bits of memory (such as BOOL, SINT, INT, DINT, REAL). Instead of using something like B10:0 thru B10:10 to hold HMI inputs to the PLC, use something like HMI_Inputs[10] in the Control Logix. This will give you 10, 32-bit words to work with. Do something similar for indications and data values in and out of the HMI. You can also make use of the User Defined data types to help organize your data and control structures.