Loop Controllers: Lone Logic is More Connected
作者:Mark T. Hoske 发表时间:2005-12-05
nced features include the implementation of EIA 485 Modbus serial communications, Watlow's Infosenset sensor technology, infrared remote communications operation, Watlow's patented User Definable Menu System, and a 'Save and Restore' feature that allows the restoration of either factory or user-defined settings. With pre-loaded instant HMI (human-machine interface) software, a Palm-brand handheld PDA device can be used to remotely program and control the Watlow Series SD controller. The wireles
s Infrared Data Communications option can support configuration and operation to facilitate recipe management and data logging and allows easier controller setup, operation, and monitoring. Devices are available in 1/32nd, 1/16th, 1/8th and 1/4 DIN panel-mount sizes. www.watlow.com Watlow

Control for harsh use

Commander line of single loop process controllers from ABB Instrumentation offers simple-to-highly-advanced control strategies and withstands harsh environments. Panel configurations include 1/16, 1/8, and 1/4 DIN; 3 x 6-in. units, and a wall/pipe mount. Most models can be configured using ABB Commander PC software, providing a fast and simple way method to set up the controllers. All can be linked to a central PLC or SCADA system using the Modbus protocol. Many standard features and options can match virtually any application. The Commander 100 1/8 DIN process controller, for example, comes with universal inputs for such process variables as temperature, pressure, flow, and level. Analog, relay and logic outputs, alarms, ramp/soak profiles, and PID control are standard. Addition of a remote setpoint option permits two or more units to operate in a master/slave (cascade) configuration. Other variants offer direct control of motorized valves and reduced case depth for installation and panel savings. www.abb.us/instrumentation ABB Instrumentation

Single, dual-loop vs. system

Single- or dual-loop microprocessor-based controllers can offer PID, velocity limiting, and lead/