Measurement-computing PC104-PDISO8 Manuale Utente Scaricare il pdf (Pagina 14)

4.2 FORM A RELAY OUTPUTS

Shown here is the schematic for a form A

relay, used at OP5 through OP7.

The form A relay has a COMMON and a

normally open (NO) contact.

When a 0 is written to the output, the

common and NO are NOT in contact. When

a 1 is written to the output the common and

NO are in contact. Figure 4-4 Form A Relay

The form A and form C relays are actually the same part number. Only the

connections to the relay poles differ.

The Pin numbers shown in Figure 4-4 correspond to the 37 pin connector when using

an adapter such as the BP40-37 or the C40-37F-2 cable

for relay #5

4.3 ISOLATED INPUTS

There are eight optically-isolated input channels. The schematic of a single channel is

shown in Figure 4-4.

Figure 4-4. Input Circuit - Simplified

Input signals are fed to a bridge rectifier so that the inputs are not polarity-sensitive.

Optical

Isolator

455 Ohm

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Measurement-computing PC104-PDISO8 Manuale Utente Pagina 14