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Cooper Bussmann BU-905U-L Wireless I/O Installation Manual
Status Outputs
The unit contains the following status outputs:
• System OK;
• Setpoint Output; and
• Communications Failure.
Status outputs are FET output to common rated at 30Vdc 500mA.
Connect the output circuit to the appropriate Status
Output
terminal. Each status output circuit is associated with an LED indicator that lights lit
when the digital output is active.
The following table details the status output behavior:
Status Output
LED
LED Status
Description
System OK active (both modules)
OK
Green
No fault detected
System OK inactive
OK
Red
• Internal fault detected.
• Supply voltage Low
• Analog Loop supply overloaded
Setpoint Output (BU-905U-L-T)
SP
Green
Local setpoint attached to 4-20mA analog input.
Communications Failure (BU-905U-L-R)
CF
Red
Watchdog alarms active on digital outputs or analog outputs.
Analog Input
The BU-905U-L-T module provides one 0-20mA DC analog input for connecting to instrument transducers (e.g. level, moisture, pressure
transducers, etc.).
Note: The BU-905U-L-T module inputs measure down to 0mA and can also be used for zero based signals (e.g., 0-10mA).
The analog input has a positive and negative terminal and can be placed at any point in the current loop, providing neither input rises above the
24 volt Analog Loop Supply level.
Each input has a loop resistance of less than 250 ohms and zener diode protection is provided against over-voltage and reverse voltage.
Note: You may require additional protection in high voltage or noisy environments or for long wiring runs.
A 24Vdc loop supply is available on the BU-905U-L-T module for powering the analog transducer loops. In this situation, connect the:
• Analog loop - between an Analog Input (-) terminal and Ground.
• Positive terminal – i.e., Analog Input (+) to the +24V Analog Loop Supply.
Externally powered loops may be connected by connecting the input between "Analog Input (+)" and “Analog Input (-)” Common mode voltage
may be -0.5V to 27V.
3A1580Rev1.7
