User`s guide

Chapter 6: Menu and Parameter Reference Series D8 User’s Guide
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• If the primary loop has only the heat output enabled, or
has the heat and cool outputs enabled, this value is the set
point when the output of the primary loop is 100 percent.
• If the primary loop has only the cool output enabled, then
this value is the set point when the output of the primary
loop is 0 percent.
Values: For a thermocouple or RTD input, any value within
the input range (see Table 6.7 on page 131). For a process in-
put, any value between the Input range low and Input range
high parameters. This value must be greater than the Cascade
low SP parameter.
Default: 25 for a thermocouple, RTD or process input.
Decimal Placement for DeviceNet: See Decimal Placement
for Numeric Values on page 59.
DeviceNet Object: Cascade (6A hex)
Ratio Menu
Use the ratio menu to configure ratio control, differential con-
trol or remote analog set point. Use these control methods to
calculate the set point of the current loop (the ratio loop) based
upon the process variable of another loop (the master loop).
For more information about ratio control, see Setting Up Ratio
Control on page 104, Setting Up Differential Control on page
106 and Setting Up Remote Analog Set Point on page 107.
Ratio Master Loop
Choose the master loop. The controller uses the process vari-
able of the master loop to calculate the set point of the current
loop.
Values: none (0), or loop 1 to 4 (1 to 4) for a four-loop con-
troller or 1 to 8 (1 to 8) for an eight-loop controller. You can-
not choose the current loop.
Default: none (0)
DeviceNet Object: Ratio (69 hex)
Ratio Low Set Point
Enter the lowest allowable set point for the current loop. The
set point will never drop below this value, regardless of the re-
sult of the ratio calculation.
Values: For a thermocouple or RTD input, any value within
the input range (see Table 6.7 ). For a process, any value be-
tween the Input range low and Input range high parameters.
This value must be less than the Ratio high SP parameter.
Default: 25
l01 Ratio r
Other menus b
l01 Ratio r
master loopbnone
l01 Ratio low r
SP b 25 ˚C