Figure 2-1. Erb-24 Block Diagram; Figure 2-2. Typical Relay Channel - Keithley ERB-24 User Manual

From
Digital
TTL
I/O
Signals
Board
115/230 V
at
50/60 Hz
FROM
DIGITAL I/O
BOARD
2-2
.
.
24 Darlington
For Relays
Transistor
0 to 23
Drivers
.
.
Power
Supply

Figure 2-1. ERB-24 Block Diagram

RELAY "X"
2.7K
DIG
7.2K
COM

Figure 2-2. Typical Relay Channel

.
.
Relays
0 to 23
.
.
+24V
NO B
MOTOROLA
ULN2803/8
3.0K
NC A
NO A
C A
Relay 0
NC B
NO B
C B
.
.
.
NC A
NO A
Relay 23
C A
NC B
NO B
C B
Notes: NC = Normally Closed
NO = Normally Open
C = Common
NC B NO A NC A
COM B COM A
NO = NORMALLY OPEN
NC = NORMALLY CLOSED
Functional Description