ABB enhances Micro-DCI process control station

-- Control Engineering, 8/1/2001

Warminster, Pa. - ABB recently introduced a triad of related Micro-DCI process control station products. The principal product in this release is the 'B' version of the 53MC5000 controller, and the latest in a long line of microprocessor based controllers from ABB that began in 1979 with the introduction of Chameleon. Like it's predecessors, the 53MC5000B incorporates physical and software modular design, is backward compatible with the 'A' model, incorporates a hot-swappable operator interface display, includes ABB's Easy-Tune self-tuning algorithm, accommodates up to four loops of control, and can be networked.

The operator interface includes a dot matrix gas discharge display and ten multi-purpose keys whose functionality is determined by the type of display currently active and the mode of operation. A family of preconfigured displays including single loop, single loop with process variable trending, two and four loops, and parameter-, status-, and alarm-displays are standard and reside in the controller's memory. Users requiring custom displays of dynamic and static information can develop their own or have ABB develop them using F-TRAN, a programming language developed for Micro-DCI controllers.

Though simple in appearance, ABB's Micro-DCI contains sufficient robustness to handle highly complex control problems using a combination of pre-configured algorithms and custom programming. Standard pre-configured control strategies include:

• PID with each term activated as necessary thus allowing P, PI, PD, and I controller implementations;
  
  
• Analog backup where the controller acts as a signal selector with another controller to provide automatic backup of a critical control strategy;
  
  
• Ratio PID for accurately maintaining the ratio between a controlled flow and to an uncontrolled (wild) flow;
  
  
• Automatic/manual (hard manual) station provides passing a signal through the controller to the output when the controller mode is automatic. In manual mode the output is an operator entered value;
  
  
• Two-loop control consists of two identical PID controllers;
  
  
• Two-loop cascade configures two PID loops and arranges traditional primary and secondary loop relationships for bumpless operation;
  
  
• Two-loop override provides two PID loops for controlling two independent variables but where neither variable may exceed pre-defined limits;
  
  
• Four loop control consists of four identical PID controllers; and
  
  
• Dual two-loop cascade provides four PID loops arranged in two traditional primary and secondary loop relationships.

For those applications not satisfied by the Micro-DCI's standard control strategies, users may select from the F-CIM (control interconnection module) library of pre-configured general-, numerical-, logical-, and control-modules to develop complex control algorithms.

For advanced control schemes such as dead-time compensation, additional numerical- and logic-operations can be applied to manipulate data using the F-TRAN programming language.

The Micro-DCI series 53MC5000B comes standard with four analog inputs, two analog out-puts, two discrete inputs, two discrete outputs, one RS-422/485 data highway and one RS-232 configuration connection. Analog inputs can be a mix of milliamp, voltage, 100 ohm RTD, and type J and T thermocouple. Users requiring additional analog and/or discrete I/O channels can choose from several module options allowing the controller to expand to include nine analog inputs, four analog outputs, two discrete inputs, two discrete outputs, and sixteen user defined discrete inputs/outputs.

For more information visit www.abbwin.com/infozone/newsletter.htm.

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