Behavior Of The Digital Outputs - Siemens SIMATIC S7-300 FM 350-1 Manual

7.3.8

Behavior of the Digital Outputs

Introduction
You can store two comparison values (Comparison value 1 and 2) on the FM 350-1 for each
counter. These comparison values are assigned to the two digital outputs (Comparison value
1: DO0, Comparison value 2: DO1). The relevant output can be set depending on the
counter level and the comparison value. This section describes the behavior of the outputs.
Comparison Values 1 and 2
You enter the two comparison values in the DB of the FC CNT_CTL1 (CMP_V1, CMP_V2)
and transfer them to the FM 350-1 by setting the bits T_CMP_V1 or T_CMP_V2 (see the
section DB Assignments (Page 169)). The count is not affected by this.
The comparison values must be within the limits of the selected count range. The
comparison value is interpreted according to the selected count range. If you give
FFFF FFFF H, for example, as the comparison value, the value is interpreted as
4 294 967 295 within the 0 to +32 bit count range, and as -1 within the -31 to +31 bit count
range.
Table 7- 16
Range of values for
comparison values
Low limit
High limit
Enabling the Outputs
Before you can activate the outputs, you must first enable them by setting the appropriate
bits in the DB (see the section DB Assignments (Page 169)). If you reset one of these bits,
the associated output is disabled immediately even if you have assigned a pulse duration for
them.
Table 7- 17
Output
DO0
DO1
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
Permissible Range of Values for Comparison Values
None
Maximum low count limit -2
Maximum high count
limit
Enabling the Outputs
Operating Modes, parameters and commands
Main count direction
Up
31
Parameterized high
count limit -1
... Is enabled by enable bit
CTRL_DO0
CTRL_DO1
7.3 Count modes
Down
1
2 - 1
31
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