GE GFK-0825F Field Recalibration

GFK-0825F Chapter 8 Datagrams 8-31
8
Field Recalibration
The 16 Point Grouped Analog Input modul e is cali brated at the factory. It can also be recali bra t ed
from the host, to adapt to differen t conditions. Calibration data consists of two sets of values for each
channel. One value i s provided to the module dur ing calibration. The other value is a correspondin g
A/D sample value for that current tha t is det er m in ed by the module. One pair of values represent s a
low value (typically 4mA) and the other represents a high value (typically 20mA).
Recalibration, if needed, is done as described below.
1. Connect a known current t o ea ch of the channels.
2. (Opti onal) Place the module in warmup mode by sending the warmup command from the host.
3. Send the calibration command from the host. The calibration command specifies the channel to
calibrate and the current being supplied to the channel's input. There is a calibrate command
for a high point and one for a low point.
4. The module samples the channel and calculates the nominal value using the default calibration
data. The module reads the number of samples specified in the command (1 to 65535) and
calculates the average. It then stores the current value and the sample average and recalculates
the scaling constant s for the channel.
5. The module returns status information about the recalibration to the BIU.
Message Content for Storing New Calibration to Field Area
Byte Value Description
70Reserved
80Reserved
9 3 Code to st ore to field ar ea
10 - 20 0 Reserved
Message Content for Reverting to Factory Calibration
Byte Value Description
70Reserved
80Reserved
9 4 Code to revert to factory calibration
10 - 20 0 Reserved
Message Content for Putting Module in Warmup Mode
Byte Value Description
70Reserved
80Reserved
9 5 Code to put module in warmup mode
10 - 20 0 Reserved