Controlling T-Buss with Modbus cuts installation costs‘It costs less to run a single pair of wires to all sensors than to run multiple pairs from each point.’ Abraham Brecher is president at Tracer Electronics, 158 Edison Rd., Lake Hopatcong, NJ 07849, which specializes in developing low-cost monitoring and control components. He can be reached at 800-523-7232. Additional information is available at www.Tracer-Inc.com. By Abraham Brecher
Simplicity and Lower Costs
Modbus and VersatilityIt is common to see a T-Buss system joined with Modbus to achieve greater convenience and versatility. In simplest terms, Modbus can be considered a structured command protocol. It employs a standard language to relay communications back and forth between a T-Buss controller and a system’s head-end computer. With Modbus as a translator, messages can be understood with any system software. If the computer requests a voltage level reading, for example, it issues a structured command and Modbus provides the data in the same manner. In practical terms, Modbus converts system messages to a standard protocol and thus accommodates equipment from a variety of manufacturers. The user is assured compatibility. Obviously, this makes installations and add-ons easier. The adjacent chart, which depicts an interface with a steam-generating system, illustrates the simplicity of T-Buss. The IDMs, all connected to the same pair of wires, monitor all system components and send data to a T-Buss controller, which in turn is connected to a head-end computer. Tied into and controlled by T-Buss are the steam generator, a separator that removes remaining water from generated steam, and a receiver that maintains pressure level and vents steam if pressure is too high. Conversely, if steam is lost, the make-up tank replaces it. The dryer removes remaining traces of water. This T-Buss system controls all pumps by means of positive feedback relays. It controls tank levels by converting analog signals into digital and sending them to the main controller. Pressure sensors monitor steam pressure, and a sensor and thermometer work together to watch the dryer’s performance. The simplicity of the system can be attributed to the fact that all components are tied into the same wire pair. Problems are flagged quickly. Adding a new component is a matter of splicing in and modifying the head-end computer’s software. It’s a supervised two-wire loop, transmitting data and power on the same pair of wires.
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Controlling T-Buss with Modbus cuts installation costs ‘It costs less to run a single pair of wires to all sensors than to run multiple pairs from each point.’ Abraham Brecher is president at Tracer Electronics, 158 Edison Rd.