Measurement Computing PCI-PDISO8 - Manual (Page 10)

10
Chapter 3
Functional Details
Relay outputs
Form C relay
The Form C relay has a common, normally open (NO) and normally closed (NC) contact. Figure 6 shows the
schematic for a Form C relay, like those connected at relay 0 through relay 4.
Figure 6. Form C Relay (0) contacts
 When 0 is written to the output, the common and NC are in contact.
 When 1 is written to the output, the common and NO are in contact.
Form A relay
The Form A relay has a common and a normally open (NO) contact. Figure 7 shows the schematic for a Form A
relay, like those connected at relay 5 through relay 7.
Figure 7. Form A Relay (5) contacts
 When 0 is written to the output, the common and NO are NOT in contact.
 When 1 is written to the output, the common and NO are in contact.
The Form A and Form C relays on the PCI-PDISO8 board are the same type. Only the connections to the relay
poles differ.