Everything You Wanted to Know About Modbus But Were Afraid to Ask
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CLEVELAND - OhioPen -- We are finding that there is an increasing need to connect to newer types of sensors that provide a digital output or other devices like displays or intelligent controllers.

What Is Modbus?

Modbus is an industrial standard communications protocol for exchanging data between devices that was developed in the late 1970s. Initially designed for communicating between programmable logic controllers (PLCs), it has grown to support a wide variety of devices including sensors, valves, drives, data acquisition equipment, and PCs.

How Is Modbus Used In Real Applications?

1. For connection to a display.

We have built many systems with data loggers connected via Modbus to LCD screens from Maple Systems to allow users to view real-time data collected by the data logger on dashboards and graphs. This eliminates the need to have a separate PC and allows the use of small portable enclosures to hold the whole system.

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2. To bring data from multiple locations in a plant back to a data logger.

A customer had multiple furnaces within a large manufacturing plant. They wanted to measure the temperature at several spots in each furnace and then bring all of the data back to a single data logger, which would save the data for record-keeping. However, because of the size and layout of the facility, it was not convenient to hardwire all of the sensors to a single logger. We built 5 remote transmitter boxes each with a wireless Modbus RTU gateway and several Modbus thermocouple input modules which could be located near the individual furnaces.

3. To bring data from multiple locations within a manufacturing campus back to a data logger.

We have a customer that has a manufacturing campus with multiple buildings within an area of several acres. They wanted to get environmental data from each of the buildings along with the temperature of freezers located in several of the buildings back into their quality control system. Similar to #2 above, we built data collection boxes for each building with a mix of Modbus input modules to suit the different types of sensors in the building, plus a wireless Modbus RTU gateway.

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4. To Simplify Calibration

We just provided a solution for a government customer with multiple laboratories in a large research facility. They need to monitor the temperature and humidity in the labs and they had a need to be able to easily calibrate the temp/RH sensors. If analog sensors were used, they would have to take the loggers and sensors offline and calibrate them as a unit. Instead, we provided them, data loggers, with two sets of sensors with a Modbus RTU interface.

For more information, contact a CAS Data Logger Applications Specialist at (800) 956-4437, or visit us at https://www.dataloggerinc.com.

CAS DataLoggers
Elizabethe Zala

Source: CAS Dataloggers

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