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C4 Manual Rev 7.5.2
3.4 Fahrenheit Operation
The C4 can use either Celsius or Fahrenheit temperature scales. Celsius is the
default mode. When the controller is operating in Celsius mode it’s behavior is
identical to the model CC-3 controller. When the controller is operating in
Fahrenheit mode, both the displays and the bus communications are different.
These differences are intentional and designed to prevent errors that might arise
from a user using setpoints in one scale while the controller is operating in the
other scale. Note, however, that there is no difference in the Program mode
programming operation of the C4 when operating in either Fahrenheit or Celsius
mode. It is incumbent upon the user to notice the differences in the temperature
displays and program accordingly.
To change the temperature scale, use SETUP mode (See Section 8) to access setup
parameter F16. Select either of these field values:
0 Celsius
1 Fahrenheit
When in Fahrenheit mode, temperature displays have an “F” following the probe
identifier on the left side of the display. Example:
p1f 102.4
Likewise, temperature inquires over the bus (PT command - See Section 7.5.7)
will return a string with an “F” as the third byte in the string. The string will
therefore be 1 byte longer than the string returned in Celsius mode. This
difference was intentional as it requires a modification of the parsing routine that
will assure that Celsius and Fahrenheit data are recognized properly. Thus, if the
current probe 1 temperature is 86.7/F, the result of a Fahrenheit mode get
temperature query for probe 1 (query command = PT1) would be
T1F 86.7<CR><LF>
If the temperature at probe 1 was 55.4/C, the same command in Celsius mode
would return
T1 55.4<CR><LF>
During Remote mode operation, the C4 may be queried to determine the current
temperature scale by using the QS, Query Setpoint, command. See Section 7.4.4.
