4-13
S7-200 Programmable Controller, CPU 210
C79000-G7076-C235-01
Addressing the Timer (T) Memory Area
Timers are devices that count increments of time. The four timers (T0 to T3) have resolutions
(time-base increments) of 100 ms. The current value of each timer is stored as a 16-bit
(word) signed integer. You access the current value by using the timer address (T + timer
number).
Format: T
[timer number]
T0
Addressing the Counter (C) Memory Area
Counters are devices that count each low-to-high transition event on the counter input(s).
The four counters (C0 to C3) provided by the CPU 210 count both up and down. The current
value of each counter stores the accumulated count as a 16-bit (word) signed integer.
Format: C
[counter number]
C2
Using Constant Values
Many of the programming instructions for the CPU 210 allow you to use constant values.
These constants can only be word-length, signed integers. The CPU stores all constants as
binary numbers, which can then be represented in decimal, hexadecimal, or ASCII formats.
Decimal Format: [decimal value]
Hexadecimal Format: 16#[hexadecimal value]
ASCII Format: ’[ASCII text]’
The CPU 210 does not support “data typing” or data checking (such as specifying that the
constant is stored as an integer or a signed integer) and does not check for a certain data
type. For example, an LDW>= instruction can use the value in MW2 as a signed integer
value, while a MOVW instruction can use the same value in MW2 as an unsigned binary
value.
The following examples show constants for decimal, hexadecimal, and ASCII format:
S Decimal constant: 20047
S Hexadecimal constant: 16#4E4F
S ASCII constant: ’AD’ (ASCII text goes between the apostrophes—also known
as “single-quote marks.”)
Basic Concepts for Programming the CPU 210
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