Siemens SINUMERIK 802S Start-Up page 68

Start-Up
4.3 Starting up the PLC
PLC project
operations, symbols and comments). The download function is intended to store all important
information of a project in a control system.
The control system is able store max. 4,000 instructions and 1,000 symbols. The
required PLC memory is influenced by the following components:
S
Number of instructions
S
Number and length of the symbol names
S
Number and length of the comments
S7–200 ladder diagram
A ladder diagram is a graphical programming language similar to electric circuit diagrams.
When creating a program using the ladder diagram form, then you will work with graphical
components to create the networks of your logics. To create your program, you can use the
following elements:
S
Contacts constitute a switch through which the current can flow. Current, however, will only
flow through a normally open contact if the contact is closed (logical
value 1). Current will flow through a normally closed contact or a negated contact (NOT) if
the contact is open (logical value 0).
S
Coils constitute a relay or an output which is updated by the signal flow.
S
Boxes constitute a function (e.g. a timer, counter or arithmetic operation) which is carried
out at the moment when the signal flow reaches the box.
A network consists of the elements mentioned above, forming a closed circuit. The current
flows from the left conductor bar (in the ladder diagram symbolized by a vertical line at the left
window) through the closed contacts, enabling coils or boxes.
Overview of commands
Table 4-7
Operand ID
V
T
C
I
Q
M
SM
AC
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In any case, the PLC 802 Programming tool manages one project (logic
Operand identifers
Description
Data
Timers
Counters
Map of digital inputs
Map of digital outputs
Flags
Special flags
ACCU
Range
V0.0 to V79999999.7 (see Table
4–8)
T0 to T15
C0 to C31
I0.0 to I7.7
Q0.0 to Q7.7
M0.0 to M127.7
SM0.0 to SM 0.6 (see Table 4–10)
AC0 ... AC3
SINUMERIK 802S
6FC5 597–2AA00–0BP2 (01.02)