Siemens SIMATIC S7-300 FM 350-1, Manual

Page: 149 / 198

Operating Modes, parameters and commands
7.4 Measuring modes
FM 350-1 Counter module
Manual, 05/2011, A5E03648639-01
149
7.4.6 Command: Open and close gate
Overview
Gates of FM 350-1:
●
A HW gate, level- or edge-triggered.
● A SW gate which you can open and close by setting control bits in the user program.
Selecting a gate
You define which gate you are going to use for the measurement in the mode interface.
The diagrams below illustrate the various options of opening and closing the gates of
FM 350-1.
Level-triggered opening and closing of the HW gate
',6WDUW
2SHQLQJRI
WKHJDWH
&ORVLQJRI
WKHJDWH
0HDVXUHPHQW
3XOVHV
Figure 7-35 Level-triggered opening and closing of the HW gate (measuring)
You open the HW gate to start the measurement by setting a signal at digital input DI-Start.
You close the HW gate to stop the measurement by resetting the signal at digital input
DI-Start. The measured value which is valid at the time the HW gate is closed is retained at
the checkback interface.
The level-triggered HW gate is activated by the first positive edge at input DI-Start DI after
you set the parameters.
With this parameter setting, the module does not evaluate input DI-Stop, but indicates its
status at the STS_STP status bit.