GE AKTA avant User Manual page 149

Digital input signals
The digital in-signal can be used to monitor external equipment by registering, for exam-
ple, error signals or event marks. An event mark can be used as a trigger for watches.
The measured digital signals can be shown as a curve in UNICORN. The unit will handle
both open/closed circuit and TTL-type voltage signals. An open circuit is interpreted as
logical 1 and a closed circuit as logical 0.
Note:
Input connection
Open circuit
Applied voltage 3.5 to 5.0 V
Closed circuit
Applied voltage 0 to 0.8 V
Digital output signals
The digital output signal can be used to control external equipment that can receive
digital signals, such as pumps or fraction collectors. The digital output signals define an
open or closed circuit, where a logical 1 will result in an open circuit and a logical 0 will
give a closed circuit. The default level, 1 or 0, is set by the user. The level can be changed
by instructions either manually, in System Settings or by a method. It is possible to send
pulses from the current level, with a pulse length of 0.1 s to 10 s.
Note:
ÄKTA avant User Manual 29035184 AE
A closed circuit is always closed against signal ground.
A closed circuit is always closed against signal ground.
4 Optional instrument modules
4.12.3 Digital connector and signals
UNICORN interpretation
Logical 1
Logical 0
4.12 I/O-box
149