ADLINK PCI-7256 - Manual (Page 32)

24 • Operation Theorem
4
Operation Theorem
4.1 Latching Relay Output
One of the innovative features on PCI-7256 is the 16-channel latching relay
output. The PCI-7256 contains only one type of latching relay : 2 coil Form C.
Figure 4.1 shows the latching relay contact arrangement under RESET
condition.
SET C
oil
1
5
+
－
2
3
4
NC
COM
NO
RE
S
E
T
Coil
10
5
+
－
9
8
7
NC
COM
NO
Figure 4.1 2 coil latching relay(RESET condition)
Each latching relay on PCI-7256 has two coils which serve as one SET coil
and one RESET coil. To control the two-coil latching relay, we need two
control bits: one for the SET coil, and one for the RESET coil. What we have
to do is to energize the SET coil and deenergize the RESET coil when
switching RESET condition to SET condition. After the contact switches to
the opposite position at a steady state, we can cut out the current on the SET
coil and the contact will not change any more. Thus the latching relay can
achieve the advantage of power saving. Under the scheme of controlling
latching relay, we define the SET condition control bits as (1,0) and the