2-2
Functional Description
Figure 2-1. ERB-24 Block Diagram
Figure 2-2. Typical Relay Channel
24 Darlington
Transistor
Drivers
Relay 0
Relay 23
Relays
0 to 23
.
.
.
.
.
.
For Relays
0 to 23
.
.
Power
Supply
TTL
Signals
From
Digital
I/O
Board
115/230 V
at
50/60 Hz
Notes:
NC =
Normally Closed
NO =
Normally Open
C = Common
.
.
.
NC A
NO A
C A
NC B
NO B
C B
NC A
NO A
C A
NC B
NO B
C B
RELAY “X”
FROM
DIGITAL I/O
BOARD
DIG
COM
2.7K
7.2K
3.0K
MOTOROLA
ULN2803/8
+24V
NO B
NC B
COM B
NO A
NC A
COM A
NO = NORMALLY OPEN
NC = NORMALLY CLOSED
