Siemens SIMATIC PCS 7 OSx - OSx Station Control; Displaying OSx Station Commands

Alarm Applications/Failover Option
A-5
SIMATIC PCS 7 OSx 4.0.0 Hardware (PA RISC)
In the normal non-alarm condition, a 24 V AC or 24 VDC supplies power to
Channel #2 common, connector 2L, through the normally-closed contacts of
the manual silence switch and Output Channel #1. When Output Channel
#2 experiences a pulsed alarm condition, the normally-open contact is
momentarily closed, supplying power to the relay . W ith the relay energized,
both of the relay’ s normally-open contacts close. These contacts allow the
annunciator both to sound and to latch on the circuit that provides power to
the relay . This occurs even when the contact on Output Channel #2 returns
to the normally-open condition.
T o silence the annunciator , either press the manual silence switch or silence
the alarm from the operator keyboard or screen. This opens the
normally-closed contact on Output Channel #1.
NOTE: If you have difficulty with your system, contact the Siemens
Energy & Automation, Inc., T echnical Services Group in the U.S.A. at
423–461–2522, or outside the U.S.A. at 49–91 1–895–7000.
Theory