Siemens Simatic CFU - Page 43

Setting the STS_DQ status bit between the comparison value and low counting limit
If the setting "Between comparison value and low limit" is selected for the parameter "Set output
DQ", the status bit STS_DQ is set in the following case:
● Counter reading < Comparison value
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Figure 5-4 STS_DQ bit between comparison value and low counting limit
Status Bit STS_DQ output
The comparison event of the counter controls the status bit STS_DQ. You can link the STS_DQ
status bit with a digital output. To do this, you have to specify a free channel as the digital output
for the comparison result in the parameters of the counter channel.
Table 5-4 Status Bit STS_DQ output
Parameters Setting of the parameter Behavior
DQ channel The DQ channel for the compari‐
son event must be a free digital
output of the CFU.
The DQ channel is assigned to the STS_DQ status bit. The user
program can no longer control this DQ channel. The status of
the STS_DQ status bit is output via the assigned DQ channel.
The remaining functionality of the DQ channel continues to be available. This affects the
reaction to the following events, for example:
● Behavior at CPU stop
● Actuator shutdown
● Diagnostics
● Error recognition
Note
● Errors of the DQ channel have no influence on the counting function.
● If STS_DQ status bit is linked with a DQ channel, this link also remains when the DI channel
is deactivated.
Operating modes and functions
5.3 Counting
SIMATIC CFU
Commissioning Manual, 08/2019, A5E39252870-AD 43