Low-level Programming
-15-
Form C relay has three contacts: NC (Normal Close), NO
(Normal Open), and CM (Common). The CM post, located at
the middle, can make contact with either NO post or NC post.
When the control bit is high (1), the CM post contacts with NO
post; If the control bit is low (0), the CM post will make contact
with NC post.
In normal power up and reset, the relay is at
low
status.
2. Form A Relay: (R5~R7 and R13~R15)
Form A relay only has two contacts: NC(Normal Close) and
CM(Common). The CM post can make contact with NO post
or not depend on the control bit. When the control bit is high
(1), the CM post contacts with NO post; If the control bit is low
(0), the CM post makes no contact with NO post.
