Application

Sequence of Operation
Wiring Diagrams
42
Siemens Industry, Inc.
Application Note, App 2928
140-1302
2015-07-07
CAUTION
A separate power supply is required if a 4-20 mA sensor is used.
Failure to follow wiring precautions will result in equipment damage.
Wiring for AI with a 4 to 20 mA Sensor.
CAUTION
Each 4-20 mA sensor requires a SEPARATE dedicated power limited 24 Vdc power
supply.
DO NOT use the same transformer to power both the sensor and the controller.
NOTE:
If the voltage/current switch is set to current and a 4 to 20 mA sensor is connected to
an AI, then special wiring requirements must be followed.
NOTE:
The controller’s DOs control 24 Vac loads only. The maximum rating is 12 VA for
each DO. An external interposing relay is required for any of the following:
• VA requirements higher than the maximum
• 110 or 220 Vac requirements
• DC power requirements
• Separate transformers used to power the load
(for example, part number 540-147, Terminal Equipment Controller Relay Module)