
Conductivity/Resistivity Analyzer/Controller
1.5.3 Deciding on a Control Strategy
All 9782 models can use relays for control
All 9782 models have at least two relays. (Two more relays are optional.) Unless dedicated to other functions, these relays can be used to control process variables using the three types of discrete control available.
∙On/Off Control using one to four cycle timers with configurable setpoint, deadband, cycle period, and “on” time.
∙PFT (Pulse Frequency Type)
∙DAT (Duration Adjusting Type)
Optional analog outputs for control
Up to three analog outputs are available as options. These current or voltage outputs can be used to retransmit a process variable using an output signal that has been scaled. An analog output that is directly proportional to an input can be used for Current Adjusting Type (CAT) control. (Despite the name of this control type, voltage outputs can also be used.)
When an output is used to retransmit a process variable, the values representing 0 and 100% outputs are configurable.
In CAT control the process values for the setpoint and proportional band limit are configurable.
Selecting a strategy
When considering whether to use On/Off control or one of the
Proportional control will usually provide faster batch treatment with less overshoot than On/Off control. However, it is important to note that
If you decide to use
9782 Series Conductivity/Resistivity Analyzer/Controller - Operator’s Manual | 7/99 |