Startup Flag; Shift Register Bits; Cursor Keys; Levels - Siemens Logo! Manual

LOGO! functions

Startup flag

Flag M8 is set in the first cycle of the user program and can
thus be used in your circuit program as startup flag. This
signal is automatically reset after the circuit program has
completed its first cycle.
The M8 flag can be used in all further cycles for setting,
deletion and evaluation procedures in the same way as
other flags.
Note
The output of the flag always carries the signal of the pre-
vious program cycle. This value does not change within
the same program cycle.

Shift register bits

LOGO! provides the shift register bits S1 to S8, which are
assigned the read-only attribute in the circuit program. The
content of shift register bits can only be modified by means
of the "Shift register" special function (see Chapter 4.4.25).

Cursor keys

Up to four cursor keys are available to you, namely C
C , C
"
grammed for the circuit program in the same ways as other
inputs. You can set the cursor keys in the corresponding
display while the system is in RUN (see Chapter 3.7.6),
and in an active message text (ESC + Key). Cursor keys
can save switches and inputs, and allow operator control of
the circuit program.

Levels

Voltage levels are designated hi and lo. A constant "1" = hi
or "0" = lo status at the block can be set by means of a per-
manent voltage level or constant value hi or lo.
Open connectors
Unused block connectors can be identified with an x.
114
and C ("C" = "Cursor"). Cursor keys are pro-
B A
,
Y
LOGO! Manual
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