ABB 266 MODBUS User Manual page 75

Setting the SP offset to barometric pressure
IMPORTANT NOTE: The user must supply either a live barometric pressure or the average for the area. If the
average pressure is used, downstream adjustments may be necessary for compensation of live to average
pressures.
Perform the following steps to set the current static pressure value to barometric pressure:
1. Disable transmitter write protection security if enabled. DIP switch 5 must be OFF before continuing. To disable write
protection follow the instructions in section 5.3.2, Disable write protection.
2. Isolate the transmitter from the measurement stream by decommissioning the transmitter using the procedure in section
5.11, Removing the transmitter from service.
3. Verify that the manifold equalizer and vent valves (Figure 47, items A, B, and C, page 58) are open and that the high (H)
and low (L) tap valves are closed.
4. Press the right soft key to access the HMI menu.
5. Use the key pad to locate and select Device Setup.
6. Check the SP reading on the HMI display.
a. If SP = The barometric pressure being used, no correction is necessary
If the SP ≠ The barometric pressure being used, proceed as follows:
b.
7. Use the key pad to locate and select Set Stat. Press. Bias> Set SP to Value. The current set point value shows on the
HMI display.
IMPORTANT NOTE: If the device does not have a current adjustment value, the displayed entry will be 0.0000.
8. Use the key pad to select Edit.
9. Use the key pad to adjust the value to the new barometric pressure in the current units of measure.
a. To enter a value, use the up or down arrow to locate the value of the first digit. When selected, press the left soft key
for Next. This moves the cursor to the next digit.
Repeat this process for each digit until the entire barometric pressure is selected. To change a digit's value after
b.
moving past it, select the Next key until the cursor reaches the incorrect digit then change it.
10. When the entry is complete select OK.
11. Once complete, use the left key to navigate back to the Operator screen. Observe that the SP value is now the current
barometric pressure.
12. Re-enable transmitter write protection security if enabled before this procedure (see section 5.3.1, Enable write protection).
Continue to section 5.13.3, Setting the DP offset to zero, to set the differential pressure offset.
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB | 67
5 Service and maintenance