VersaPro Temperature Controller
Page 44
Copyright © 2013, United Process Controls Inc.
All rights to copy, reproduce and transmit are reserved
15
Scaling Analog Outputs
The analog outputs are scaled to simple offset and span values. For example if analog output 1 were to be
scaled for a 0 to 2000° value, the offset value would be 0 and the span value would be 2000.
It is possible to narrow the response to the process even if the instrument can measure a larger process range.
If a smaller range of temperature is to be retransmitted it would be necessary to change the offset value to the
lowest value to be retransmitted. The span would be set to the highest value. For example if a temperature
span of 1000° to 1500° was to be recorded then the offset would be 1000, the span would be 1500 and the full
4mA to 20mA range would respond to this range of temperature.
The same rules apply to analog output 2. The range of the offset and span numbers depends on the range of
the process value that has been selected for either analog output.
Additional selections for Power Output and Program mode have fixed offset and span values. The power
output offset and span values are fixed to the LOPO and HIPO values selected for the control outputs under
the Setup Control menu.
The Program mode selection has a fixed offset of 0 and a fixed span of 4096. When this output mode is
selected the analog output can only be changed by writing a value to either the DACV1 or DACV2 registers.
16
Calibration
There are two analog inputs, a cold junction compensation sensor, and two analog outputs on the VersaPro.
The input level is determined by which terminals are used for the input signal. There are two pairs of input
terminals: TB-B 1, 2 for the thermocouple (T/C) input and TB-B 3, 4 for the probe millivolt input.
The 4 – 20mA analog outputs are at TB-B 5, 6 and TB-B 7, 8.
The following is a brief description of input/output and its specifications.
a) T/C
Input
Input
range
-10
to
+70
millivolts
2
V
TC
burnout
>full
scale
b)
Probe mV Input
Input
range
-50
to
+2000
millivolts
.1 mV, linear
Input
impedance
40
megohm
Open
input
>full
scale
c) Output
1
Output
range
0
to
20
milliamps
Max.
Load
650
ohms
d) Output
2
Output
range
0
to
20
milliamps
Max.
Load
650
ohms
