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
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
What does EINZ mean when it appears in a program.
Appreciate if someone can advise.
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
(another wild guess) it could be literally 'one' or 'single' or its an
input to a function/subroutine.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.