- Controller loops management
Controller loops management
Control Type: There are five control types available in C-BIO:
SUP (Supervisory) A non-feedback control loop that utilizes a calibrated analog input scaled to an analog output to achieve control. It is assumed that the output device is linear. An example of a supervisory loop is agitation speed where the agitation motor has its own controller. The PID terms are not functional with Supervisory control.
MOD (Modulated) A feedback control loop with an analog output. The analog output is modulated according to the PID values to maintain the measured value equal to the set point.
DDC (Direct Digital Control) A feedback control loop where one or two digital outputs are actioned to achieve control. An example is temperature. See DDC Out mode below.
DDC2 Same as DDC. Allows the storage of an alternate configuration of the same controller. This is useful for storing a sterilization configuration of a temperature controller.
CAS (Cascade) Similar to Modulated, except that control is achieved by modifying the set point of the slave controller. A common example is the dissolved oxygen controller in cascade mode with agitation speed as the slave analog TAG. In Cascade mode, the watch dog (WD) alarms of the slave’s controller become the upper and lower bounds for the slave’s set point. In the example of dissolved oxygen cascaded to agitation speed, the WD alarms of the agitation controller become upper and lower bounds for speed set points from the dissolved oxygen controller. This is useful to prevent under or over mixing of a culture.
ALGO (Algorithm) Similar to Cascade, except that control is achieved by modifying the set point of one or several slave controllers. A common example is the dissolved oxygen controller in algo mode with agitation speed in the first slave, then AIR massflow in the second slave, O2 massflow in the third slave and N2 massflow in the fourth slave, when these controllers are configured options (a detailed example is defined below explaining the various parameters).
Configuration of MODE ALGO: when this mode is selected several parameters detailed above are not display:
– Cycle time
– Constant of time
– Output Mode DDC
– Digital Out Tag X
– Analog Out Tag
– Slave Analog Tag
You can choose to configure one or 2, 3 and 4 slave controllers depending on your configuration.
1) Volume Type: two types of volume are selected, variable volume or constant volume. If you choose variable volume, the control shall be on the selected parameters for each slave regardless of the total volume of gas added. But if you choose constant volume, the control shall be on the selected parameters for each slave according to the constant volume before so it is not exceeded. The total volume of gas added should not exceed the constant volume requested.
2) Dead Band (% of the scale divided by 20): selects the percent of range in which the Integral and Derivative terms are used for control. Outside the selected range only the Proportional term is used. This enhances the speed at which the measured value approaches the set point and reduces the amount of integral wind up.
3) Slave 1: configuration of slave 1, if configured tick the case, otherwise untick the case. If the volume type is Constant Volume, the first slave has to be the speed agitation (see the second picture above). This slave is reserved for a controller that works in DIRECT.
4) Slave 2: configuration of slave 2, if configured tick the case, otherwise untick the case. This slave is reserved for a controller that works in DIRECT.
5) Slave 3: configuration of slave 3, if configured tick the case, otherwise untick the case. This slave is reserved for a controller that works in DIRECT.
6) Slave 4: configuration of slave 4, if configured tick the case, otherwise untick the case. This slave is reserved for a controller that works in REVERSE (for example nitrogen).