Digital Temperature Controller Reference Manual

3.3.3 Recipes
DTC CONFIGURATION
As of DTC version 2.I an unlimited amount of temperature recipes can be stored. Older
DTC’s can store a maximum of 16 recipes. The recipes can be selected manually with the
Touch Screen or TSC-II or automatically via the DPC or by using the digital inputs on the
rear connector if no DPC is present.
All the zones include ramping as part of the recipes, thus ensuring the temperature rises at a
controlled rate. This prevents furnace, tube or muffle damage due temperature shock. An
external timer can switch the DTC from one recipe to another. This can be used as an energy
saving feature that allows the temperature of the furnace to be lowered at nights and
weekends.
3.4 Independent or Master/Slave Control
The control zones normally operate in the Independent (I) mode. In this case, all the zones
are completely independent of each other. However, the possibility exists to operate four or
five zones (Slaves) under the control of another (Master). This is known as Master/Slave
Control (MS). In this configuration the center zone (2 in a 3-zone furnace, 3 in a 5-zone
furnace) is the master.
All other zones operate normally as if they were independent zones. However, if during a
ramp up or a cool down the master cannot follow its temperature setpoints, the Master/Slave
loop becomes active. The deviation of the master from its setpoints is subtracted from the
temperature setpoints of the slaves. This results in the same actual temperature for all three
zones.
When the furnace is not ramping, the Master/Slave loop becomes active if the deviation
from the setpoints in the master is greater than 5 ºC.
This configuration will only work correctly if the master is slower than the slaves. If this is
not the case, either the gain value of the slaves has to be increased or the gain value of the
master has to be decreased.
A comparison of the zone temperatures for both types of control is given in Figure 3-2.
Figure 3-2 Independent and Master/Slave control
DIGITAL TEMPERATURE CONTROLLER REFERENCE MANUAL 3-4