Specifications
Analog Input Modules
44
31007715 6/2008
STB AVI 1255 Field Wiring
Summary The STB AVI 1255 module uses two six-terminal field wiring connectors. Analog
sensor 1 is wired to the top connector, and analog sensor 2 is wired to the bottom
connector.
Connectors Use a set of either:
z two STB XTS 1100 screw type field wiring connectors (available in a kit of 20)
z two STB XTS 2100 spring clamp field wiring connectors (available in a kit of 20)
These field wiring connectors each have six connection terminals, with a 3.8 mm
(0.15 in) pitch between each pin.
Field Sensors The STB AVI 1255 module handles analog input data from two 0 to 10 V single-
ended analog field sensors. Data on each channel has a resolution of 10 bits. The
module supports two-, three- and four-wire devices that draw current up 100 mA/
module.
If you want to maintain the module’s built-in isolation between the analog portion of
the module and the island’s sensor bus, you can make only two-wire connections.
Field Wire
Requirements
Individual connector terminals accept one field wire. Use wire sizes in the range
0.5...1.5mm
2
(24 ... 16 AWG).
Shielded twisted-pair cable is recommended. The shield should be tied to an
external clamp that is tied to functional earth.
We recommend that you strip at least 9 mm from the wire’s jacket for the module
connection.
Field
Wiring Pinout
The top connector supports analog sensor 1, and the bottom connector supports
analog sensor 2. Four field wires may be used on each connector—on pins 1, 3, 4
and 6.
The connections on pin 1 and pin 6 are optional, and using them defeats the built-in
isolation between the analog portion of the module and the island’s field power bus.
No connections are made on pins 2 and 5 of either connector:
Note: An open circuit in the input cabling causes a voltage with an indeterminate
value to be reported.
Pin Top Connections Bottom Connections
1 +24 VDC from field power bus for field
device accessories
+24 VDC from field power bus for field
device accessories
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