Rockwell Automation 1440-SPD02-01RB XM-220 Dual Speed Module - Manual (Page 56)

Publication GMSI10-UM004B-EN-P - May 2010
48 Configuration Parameters
Controls whether a small amount of current is
injected into the sensor wiring to help detect
transducer faults of passive magnetic sensors.
Passive magnetic sensors are unbiased and provide
no inherent fault detection capability. The XM-220 is
able to detect an open or short circuit from the input
to the sensor using the resistance of the passive
magnetic sensor and a configurable bias current per
channel. To use this feature, the resistance of the
magnetic sensor must be a minimum of 350 ohms. In
an open circuit situation, the Transducer DC bias
measurement will read approximately 18 volts. In a
short circuit situation, the Transducer DC bias will
read near 0 volts. Under normal operating conditions,
the Transducer DC bias can range from 0.12 to 3
volts depending on the sensor DC resistance and
temperature. This DC bias may also vary between
XM-220 devices. It is recommended that the Fault
Low and Fault High be set to 0.2 and 7,
respectively.
The bias current parameter also adjusts the
auto-trigger detection algorithm for passive
magnetic signals.
Important: If you are using passive
magnetic sensors, then you must
enable the bias current if:
•
You want to use auto trigger mode.
•
You want to detect transducer fault
conditions.
Fault Low The minimum, or most negative, expected DC
voltage from the transducer. Volts
Note: A DC Bias voltage reading
outside this range constitutes a
transducer fault.
Important: If you are using passive
magnet sensors, it is recommended
that the Fault Low and Fault High be
set to 0.2 and 7, respectively. See
Bias Current parameter for details.
Fault High The maximum expected DC voltage from the
transducer.
Tachometer Parameters
Parameter Name Description Values/Comments
XM Configuration
Utility EDS File
Enable Bias
Current Bias Current
XM Configuration
Utility EDS File
Check = Enable Enabled
Clear = Disable Disabled