Supported Dryer SPI Commands
SPI protocol defines two different modes, “Select” and “Poll”. “Select” commands
are used to set or change the information in the dryer. For example, to change a
temperature setpoint from 200°F to 250°F {93°C to 121°C} a “Select” command
is used. “Poll” commands are used to read the information without changing or
modifying it. For example, when you simply want to display the actual process
temperature. In either case two hex command bytes are sent to the equipment to
specify what communication action to take.
The following list shows the “Select” and “Poll” bytes along with a description of
the information that may be retrieved from Conair dryers.
1. Echo - Allows the master to test a piece of equipment by writing 4 bytes of
information to the equipment and then reading it back.
Select: 20h, 21h Poll: 20h, 20h
2. Version - Read the SPI version from the equipment.
Select: NA Poll: 20h, 22h
3. Setpoint Process Temperature - Sets and retrieves the process temperature
setpoint.
Select: 20h, 31h Poll: 20h, 30h
4. Alarm, High Temperature Deviation - Sets and retrieves the high temperature
deviation alarm setpoint. Not that in Conair dryers there is actually only devia-
tion setpoint that is used for both high and low temperature deviation. The last
value written to either the high or the low will be the value that is used.
Select: 20h, 33h Poll: 20h, 34h
5. Alarm, Low Temperature Deviation - Sets and retrieves the low temperature
deviation alarm setpoint. Not that in Conair dryers there is actually only devia-
tion setpoint that is used for both high and low temperature deviation. The last
value written to either the high or the low will be the value that is used.
Select: 20h, 35h Poll: 20h, 34h
(continued)
D-4 l SPI Comm un ica tions
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