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In the dual port, activation of a function is performed by the communication processor writing the
value 0x0AA to a given location. When acknowledged, the location is cleared to the value 0x055.
By communication, activation of a function is performed by issuing a write (the value is
unimportant) to a given Modbus register. When acknowledged, the register will read 0x00055.
In order to modify any calibration information, it is necessary to enter Calibration Mode.
Calibration Mode is entered by writing to Modbus Address 57365 (0x0E014), which starts a 30
second timer. While in Calibration Mode, bit 3 of the 196 Health Status register is set. It is only
while in Calibration Mode that all of the other above features will operate. This register can either
be written to prior to each and every above listed action, or continuously at a rate more frequent
than every 30 seconds.
The Manual Reference Calibration instructs the meter to test the voltage levels provided by the
reference chip. This is used to adjust for gradual changes in offset and gain as a function of time or
temperature. Reference Calibrations are automatically performed every 12 hours, or when the
internal temperature changes by more than 1.5 degrees C after at least 15 minutes from the previous
reference calibration.
The meter contains two sets of calibration tables - a Factory Table, and a Customer Configurable
Table for CTPT Compensation. Operation with CTPT Compensation can only take place if CTPT
Compensation is enabled in the Programmable Settings and if a valid CTPT Compensation
Calibration has been performed; otherwise, the factory calibration is used. If the CTPT
Compensation factors are being used, then bit 4 of the 196 Health Status register is set.
In order to perform the first CTPT Compensation Calibration procedure, the Programmable Setting
must be enabled and Modbus Register 57365 (0x0E014) must be written. This activates CTPT
Compensation Calibration, even though a valid calibration has not yet been performed. Next,
Initial Values must be provided by writing to Modbus Register 57367 (0x0E016).
The Autocalibration of Gains is performed by selecting a Range and initiating Autocalibration.
First, the appropriate inputs should be applied to the meter. Then the appropriate Range should be
selected by writing to Modbus Register 57349-57355 (0x0E004-0x0E00A). Finally, Autocalibration
should be initiated by writing to Modbus Register 57356 (0x0E00B).
Manual Adjustment of Calibration Values is performed by selecting Gain vs. Phase Compensation,
indicating whether Adjustment should be 1 count or 10, selecting a Range and then by indicating
which Phase should be incremented or decremented. First, either Gain or Phase Compensation
Adjustment should be selected by writing to Register 57366 (0x0E015) or 57368 (0x0E017). Next,
1 or 10 count Adjustments should be selected by writing to Register 57369 (0x0E018) or 57370
(0x0E019). Then the appropriate Range should be selected by writing to Modbus Register 57349-
57355 (0x0E004-0x0E00A) or 57373-57377 (0x0E01C-0x0E020). Finally, indicate which Phase is
being adjusted and in which direction by writing to Modbus register 57357-57364 (0x0E00C-
0x0E013).