Rockwell Automation 1746-FIO4V SLC 500 Fast Analog I/O/ User Manual - Manual (Page 70)

Publication 1746-UM009B-EN-P - September 2007
70 Test Module Operation
Test Analog Inputs
Before testing the module’s input channels, the SLC 500 system must
be installed and tested according to the SLC 500 Modular Hardware
Style User Manual, publication 1747-UM011.
The processor must be connected to a programming device, properly
configured, and must have no rungs in its ladder program. The
module’s LED indicator must also be illuminated.
If your input sensors can be manually varied over their normal
operating range, use them to test the input channels. If not, use a
replacement voltage or current source after disconnecting the sensor.
For example, substitute input voltages for 1 mA, 5 mA, and 20 mA
inputs would be 0.25, 1.25, and 5.0V, respectively. Do not exceed 5V.
In normal operation, a voltage source should not be connected to an
analog input channel in the current mode.
1. Determine the limits of the sensor’s signal range for the channel.
For example, if the sensor has an output range of 1…5 mA, the
lower limit is 1 mA and the upper limit is 5 mA.
2. Compute the decimal value that should appear in the
processor’s input image table for the sensor’s lower and upper
signal limits at the input channel.
For example, limits of 1 mA and 5 mA would have typical
decimal values of 407 and 2047, respectively. If necessary, refer
to the section, Converting Analog Input Data, in chapter 4.
ATTENTION
Do not attempt to test the module’s input channels unless its
process control output devices have been disconnected,
inhibited, or replaced by a passive load.
IMPORTANT
If a current source is not available to test a current input
channel, carefully apply a substitute input voltage instead.
Determine the substitute input voltage using this formula.
Voltage Input (V) = Current Input (mA) x 0.25