User guide

Programming Reference
4-3
The 10-bit analog input can be used for speed reference or trim reference. Refer to
figure 4.4. The input is jumper-selected between voltage or current signals in the
range 0 to 10 volts or 0 to 20 mA.
The data from the analog input is normalized so that 4095 corresponds to positive full
scale. The RMI board reads the analog input every scan (1.0ms) and computes a
running sum over four scans. After summing, the RMI board adds the input offset and
multiplies by the gain. The offset adjustment is used to compensate for analog offsets
to compensate for minimal speed setting, and to support a bi-directional speed
reference. When the gain is a negative value, the input signal will be inverted.
The frequency input can be used for speed or trim reference. Refer to figure 4.4. The
input operates from 0 to 200kHz. The RMI board samples the number of cycles
detected every scan (1.0ms) and computes a running sum of the last N scans. The
number of samples is selected in r.014.
If the number of samples is greater than 20, it is rounded up to the next multiple of 20.
The running sum is limited to a maximum value of 32000.
After summing, the RMI board adds an offset and multiplies by a gain. Offset
adjustment is used to compensate for minimal speed setting and to support a
bi-directional speed reference. When the gain is a negative value, the input signal will
be inverted.
Important: The running sum will be limited to 32000. Do not set the number of
samples too high.
r.010, r.011 Analog Input
Par. Parameter Name Type Default Step Range
r.010 Analog Input Offset Tun able 0 1 – 3700 to +3700
r.011 Analog Input Gain Tunable 1.000 0.001 – 5.000 to +5.000
r.014, r.015, r.016 Frequency Input
Par. Parameter Name Type Default Step Range
r.014 Frequency Input Sample Period Tunable 5 1 5 to 500
r.015 Frequency Input Offset Tunable 0 1 –2048 to +2048
r.016 Frequency Input Gain Tunable 1.000 0.001 –5.000 to +5.000
Running Sum Example
For a 200 kHz reference frequency and 500 samples:
Number of Samples x Reference Pulses per ms = Running Sum
500 x 200 = 100,000
Note that with a 200 kHz reference frequency, the number of samples must be
reduced to about 160:
160 x 200 = 32,000