Being somewhat unfamiliar with Step 5 programming (more familiar with Allen Bradley), appreciate if someone can advise on the following block that forms part of a program: FB10 Segment 1 Name : AUTOMAN DECL : STAT I, W : L = STAT : C DB20 : T DW11 : BE What does the DECL : STAT I, W do, and what does the = STAT do?
In another block, STEU is a control word in the program, what does this actually do? What does EINZ mean when it appears in a program.
Appreciate if someone can advise.
TIA
The AB uses the concept of files to structure the program data. You probably create at least one binary, one integer, etc... file to work with the older AB PLCs. You may even create more than one (say) binary file, one file for valves, one file for motors, etc. The S5 is a little different, it uses Data Blocks to create structure in the PLC data. The DBs are not typed, like the AB, instead you can mix types in them. I guess the idea is to sort data by code block, rather than data type. Its quite common to block the PLC data by plant area rather than device type (although, like all Siemens stuff, its all up to you - or whoever programmed the PLC.
FB10 is a little subroutine that looks like it takes a WORD and shifts it into a DataBlock (DB). Depending on who programmed this, I would hazard a guess that the DB is used for linking to an HMI or display.
The code really defines a function that has one 'command line input' so to speak. Its a little unusual because if it were code for a (say) motor then we would expect to see more than one motor and so we would expect to see the status info shifted to more than one 'slot' in the DB. If I knew how this was called in the code I could tell you for sure.
_If_ it is a PID block (OB251) then: Bit 0 is Auto/Man Bit 1 switches derivative internal or external Bit 2 controller On/Off Bit 3 position or velocity algorithm Bit 4 output either goes straight from manual to auto value or goes through a low pass filter Bit 5 selects feedforward control Bit 6 setpoint and manual output uses floating point Bit 7 process value is floating point Bit 8 on some PLCs this will select bumpless transfer from Man to Auto. Bit 5
(another wild guess) it could be literally 'one' or 'single' or its an input to a function/subroutine.
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