Chapter Two
Installation
man_105_2.9.doc
Page
19
the loop can be powered be either the 105U or the device. Externally powered loops to 27 VDC
may be connected by connecting the output between the "AO” terminal (positive) and the
"COM" terminal (negative). Zener protection of analogue outputs provides protection against short
periods of over-voltage but longer periods
may result in module damage
.
Note that the 105 common is connected internally to ground and no other point in the analogue loop
should be grounded. If the external device has single-ended grounded inputs, then a signal isolator
must be used.
Analogue outputs may also be configured to individually turn off (0 mA) if no command message is
received to that output for a certain period. . See Chapter 4
Configuration
for further details.
_
+
+24V
AO 1
COM
105U
DEVICE
_
Note:
COM on 105U is
connected to
ground/earth. If
the external power
supply cannot be
grounded, a loop
isolator must be
used.
+
Connecting to a floating input device, powered from the 105U
+24V
AO 1
COM
105U
+V
-
V
DEVICE
+
+24V
AO 1
COM
105U
_
Connecting to an externally powered floating-input device
+V
DEVICE
AI
+24V
AO 1
COM
105U
Signal
Isolator
Connecting to a grounded input device via a signal isolator