32
3-2-4 Direct/Reverse Operation
The direct/reverse operation parameter is the same for all control points.
Reverse operation is used for heating control and direct operation is used for
cooling control.
The default is 0000, i.e., all control points will operate in reverse (heating con-
trol).
3-3
Set Point and Process Value
The setting for the set point used to control the temperature and the process val-
ue includes a temperature unit and a setting unit.
The temperature unit (
°
C or
°
F) is specified using pin 6 of the FUNCTION switch
on the front panel of the Unit. Refer to 2-3 Setting Selectors and Switch for de-
tails on settings.
The setting unit is set using the setting unit parameter as either 0 or 0.1 (default).
If serial communications are used to read the set point and process value data, 4
digits will be indicated if the setting unit is “0” and 5 digits will be indicated if the
setting unit is “0.1.”
The same setting unit is used for all control points.
3-3-1 Setting Set Point
Set the set point using the Set Point Write (WS) command in each memory bank
of each control point.
If DeviceNet communications are being used, the values in the memory of the
host devices will be automatically reflected in the settings.
The default is 0.0
°
C or 0.0
°
F.
3-3-2 Reading Process Value
Read the process value using the Process Value Read (RX) command. The pro-
cess value will be read for each control point.
If DeviceNet is used, the values in the memory of the host device will be automat-
ically read.
The setting unit is used as the unit for the alarm temperature and current control
temperature during ramp control, as well as for the set point and process value.
The settings will not be affected if the setting unit is changed. If the settings are
read, however, they will be indicated as follows:
•
If the setting unit is set to 0.1, and data is read after changing the setting unit to
0, any value after the decimal point will be rounded off to a whole integer. For
example, 1234.5 will be read as 1235.
•
If the setting unit is set to 0, and data is read after changing the setting unit to
0.1, a zero will be added after the decimal point. For example, 1234 will be read
as 1234.0.
Operation Start and Stop
•
Execute the Operation Start (OS) command for each control point to start tem-
perature control.
•
Execute the Operation Stop (OP) command to stop temperature control or
manual operation.
•
When DeviceNet communications are used, specific bits are allocated in the
memory of the host device for starting and stopping temperature control. Tem-
perature control is started and stopped by turning the corresponding bit ON or
OFF.
Setting Unit
Set Point and Process Value
Section 3-3
