Configuring the MSC loop - Verasys - LIT-12013364 - LC-VAC1000-0 - Smart equipment controller - VAC1000 - 4.2

Verasys Sideloop Controller Application Note
Brand
Verasys
Product name
VAC1000
Document type
Application Note
Document number
LIT-12013364
Version
4.2
Revision date
2021-07-16
Product status
Active
Language
English

The MSC loop provides sequences to control equipment with multiple stages. The MSC loop handles interstage delays, minimum on and off timers, and controls the limits to turn on and off each stage. The MSC loop can control up to six stages. You can configure the MSC loop strategy as a reset span, PID control, or PID control with reset. Different options appear depending on the configuration chosen.

To configure the control loop, complete the following steps:

Note: The MSC loop controls the binary outputs based on the number of stages. You can select the input for the control loop.
  1. Enable the unit: Details > System Configuration > General > Unit Enable.
  2. Enable the control loop: Details > System Configuration > General > Multistage Control Loop Enable.
  3. Select the number of stages: Details > System Configuration > General > Number of stages.
  4. Select the control loop strategy: Details > Multistage Control Loop > General > MSC Output Control Selector.
  5. Enable interlock, if required: Details > Multistage Control Loop > General > Binary Interlock Enable.
  6. Define minimum on and off times: Details > Multistage Control Loop > General > Min On Time and Min Off Time.
  7. Configure the selected control loop strategy. For more information, see the relevant section:
  8. Configure the interlock strategy, if required. For more information, see Configuring the MSC loop interlock.

Configuring the reset span strategy for the MSC loop

The reset span strategy spans an input range and provides the corresponding output value in the output range that passes to the MSC block. You can define both the input range and the output range.

Note: Make sure that you select the number of stages present in the system.
Figure 1. Reset span strategy example

To configure the strategy, complete the following steps:

  1. Navigate to Details > Multistage Control Loop > Simple Reset.
  2. Select one of the following inputs types: SAB sensor, wired Analog Input (AI) sensor, or network shared sensor.
  3. Configure the span block input low limit and high limit, and the corresponding span block output low limit and high limit.

For the full list of parameters and their details, see Table 28.

Configuring the PID control strategy for the MSC loop

The PID control strategy uses PID tuning to control an output process variable to a network setpoint. The output then passes to the MSC block. You can define both the process variable, for example, ZN-T, and the network setpoint value.

Note: Make sure that you select the number of stages present in the system.
Figure 2. PID control strategy example

To configure the strategy, complete the following steps:

  1. Navigate to Details > Multistage Control Loop > Remote Setpoint FB Control.
  2. Select one of the following inputs types: SAB sensor, wired AI sensor, or network shared sensor.
  3. Configure the network setpoint, PID type, and tuning type.
  4. Configure the PID manual or automatic tuning parameters. Automatic tuning uses a number of predefined settings depending on the type of process being controlled.

For the full list of parameters and their details, see Table 29.

Configuring the PID control with reset strategy for the MSC loop

The PID control with reset strategy sets a network setpoint and uses PID tuning to control an output process variable to that setpoint. The output then passes to the MSC block. To set the network setpoint, the strategy uses an input range, and provides the corresponding output value in the output range. You can define the input range, output range, the process variable, for example, ZN-T, and you can select the setpoint that the strategy resets based on the input.

Note: Make sure that you select the number of stages present in the system.
Figure 3. PID control with reset strategy example
  1. Navigate to Details > Multistage Control Loop > Setpoint Reset from Input FB Control.
  2. Select one of the following inputs: SAB based sensor, wired AI sensor, or network shared sensor for process variable and setpoint.
  3. Configure the span input low limit and high limit, and the corresponding span output low limit and high limit.
  4. Configure the PID type and tuning type.
  5. Configure the PID manual or automatic tuning parameters. Automatic tuning uses a number of predefined settings depending on the type of process being controlled.

For the full list of parameters and their details, see Table 30.

Configuring the MSC loop interlock

  1. Navigate to Details > Multistage Control Loop > Binary Interlock.
  2. Configure the interlock mode, select a binary input, and configure the delay type and the delay times.
    Note: If the interlock is in control mode, the control loop works according to the state of the selected binary input. State 1 activates the control loop and state 0 disables the control loop and sets the output to 0% and turns off all stages.

For the full list of parameters and their details, see Table 31.