B873-002 and B875-002 Calibration
(Original Document)
About us
Required Tools
Calibration is recommended at 12 month intervals for operation at or below 405 C (1045 F) and at 6 month intervals between 405 and 605 C (1045 and 1405 F).
The following tools are needed to calibrate a B873-002 or B875-002 module in a running system:
1.
A programmer
2.
A precision voltmeter
3.
An Analog DC Voltage/Current
4.
A 1/4 inch Phillips screwdriver
5.
A 1/8 inch standard screwdriver
6.
An adhesive for the trim pot adjusting screw (e.g. Locktight Glyptol)
Calibration Adjustments
To achieve full accuracy of the module, allow it to warm up for one hour with a valid input present at the channel to be used for the calibration. Without warm up, the accuracy of the data values will be +/-%2 counts.
Steps to Calibration
The adjustments can be made using a voltage or current source. Use steps 5a through 10a for voltage or steps 5b through 10b for current.
1.
Remove trim pot access cover, located on the front panel.
2.
Open module handle to expose connector(s) and terminal(s).
3.
Unplug field wiring connector(s).
4.
Set up Programmer to monitor the register for the channel used for calibration.
Method using a voltage source:
5a.
Connect the positive lead of the voltage source to the channel's input + terminal and the negative lead to the channel's input - terminal.
6a.
Set voltage source to output 1.00048 volts.
7a.
While monitoring the register, adjust the top trim pot until the value toggles between 0000 and 0001 (Standard) or 4095 and 4096 (Elevated).
8a.
Use an adhesive to secure the adjusting screw on the trimmer.
9a.
Set voltage source to output 4.99951 volts.
10a.
While monitoring the register, adjust the bottom trim pot until the value toggles between 4095 and 4096 (Standard) or 8191 and 8192 (Elevated).
Method using a current source:*
5b.
Connect the positive lead of the current source to the channel's input + terminal and the negative lead to the channel's input - terminal.
6b.
Set current source to output 4.002 mA.
7b.
While monitoring the register, adjust the top trim pot until the value toggles between 0000 and 0001 (Standard) or 4095 and 4096 (Elevated).
8b.
Use an adhesive to secure the adjusting screw on the trimmer.
9b.
Set current source to output 19.998mA.
10b.
While monitoring the register, adjust the bottom trim pot until the value toggles between 4095 and 4096 (Standard) or 8191 and 8192 (Elevated).
11.
Disconnect input source.
12.
Re-connect field wiring.
13.
Close module handle.
14.
Replace trim pot access cover.
* To use this method, a jumper must be connected between the Current Sense terminal and the Input + terminal of the channel to be calibrated.
Input to Data Value Conversion
The following figure shows the Input to Data Value Conversion chart.
Calculation for determining Data Value (refer to the figure above and the table below):
Voltage:
(Input Voltage - 1) X 1024
Example: (Refer to Graph)
(4.4521V - 1) X 1024
3.4521 X 1024 = 3534.9504 (Add 4096 for Elevated Value)
Data Value = 3535 Standard 7631 Elevated
(Rounded to the nearest whole number)
Current:
(Input Current - 4) X 256
Example: (Refer to Graph)
(13.078mA - 4) X 256
9.078 X 256 = 2323.968 (Add 4096 for Elevated Value) 


 Data Value = 2324 Standard 6420 Elevated               


 (Rounded to the nearest whole number)               


               


               


Data Value Reference Chart               


The following is the Data Reference Chart for the B873-200 & B875-200 Modules.               



















Standard               






Elevated               






Input Voltage, Current, or Condition               












0000               






0000               






1. First three seconds after power up               



2. During failure recovery               











0000               






4095               






Under range               











0000               






OFF               






1.0000V or 4 mA               











4095               






4096               






4.999V or 19.995 mA               











4095               






8192               






Over range