Articles and Technical Papers
Data-Linc Group: Its Niche and Latest Development
A-B Journal (June 1997)
Data-Linc Group, with headquarters in Redmond, Wash., manufactures a broad line of industrial-grade modems for wireless (license free 902-928 MHz and 2.4-2.4835 MHz), dial-up/leased line, fiber optic, and wire data transmission. You can visit their web site at www.data-linc.com, which includes two sections devoted to Rockwell Automation and Allen-Bradley.
Q: What modem applications do you focus on?
Data-Linc does not focus on just one type of application or industry. They manufacture wireless, dial-up, fiberoptic, leased line, and FSK wire modems as well as multiplexers. Data-Linc modems support uncompressed data rates up to 115.2 Kbaud and range capabilities up to 90 miles wireless or 20 miles on any two-conductor wire. They support point-to point, multi-point, and multi-tier/multi-drop applications, and all Data-Linc modems can even be chassis mounted in Allen-Bradley PLC-5 and SLC 500 Series enclosures. Therefore, their products can be beneficial for a variety of purposes in different industries.
Simply stated, the company's forte is industrial modems. They have established their business niche as industrial data communications experts offering simple installation. Data-Linc modems are always custom configured at the factory for each application to ensure easy and successful installation. The customer tells Data-Linc what equipment the modems will connect to, and both modems and connecting cables are labeled showing the customer exactly what they should be hooked up to. The customer does not have to deal with modem field settings, programming, or adaptors. Data-Linc provides this service at no additional charge.
Q: In what industries are Data-Linc modems being used right now?
One installation that stands out is Arco Petroleum/Vastar Resources. They needed to transmit data between Allen-Bradley SLC 5/03 processors located on oil platforms 11 miles apart and in a particularly high-interference environment in the Gulf of Mexico. No other license-free radio modem that Arco/Vastar tested could reliably maintain communication. Data-Linc SRM6000 frequency hopping spread spectrum radio modems (no site license required) successfully eliminated the data transmission problems. Three other examples of applications are:
- Data-Linc SRM6000 license-free radio modems are utilized in a very high shock and vibration environment to transmit data from the cockpits of the Budweiser and Pico American Dream hydroplanes back to the pits.
- Data-Linc MDL500 series FSK wire modems are installed in a conveyor and material handling system to communicate data over a set of conductor rails as well as with a festooned system to and from an Automated Guided Vehicle (AGV) system.
- Data-Linc SRM6000 frequency hopping spread spectrum radio modems transmit data between a PC and Allen-Bradley PLC 5/30 processors with RS-422 interface to provide crane control.
Data-Linc modems are designed for the most challenging industrial environments. They operate successfully at -40°C to +75 and 85°C in the temperature extremes of the Val d'Or region of Northern Quebec and Dubai in the Middle East. They are used in aluminum reduction plants because of their resistance to electromagnetic interference. Data-Linc FSK wire modems are also used in industries where data has to be moved across sliding contacts, slip rings, or moving wheels. Data can even be superimposed on AC/DC power lines, PBX telephone wires or instrumentation lines, thereby eliminating additional cable installation.
Q: What is Data-Linc's latest development?
Data-Linc has developed the ability to provide half duplex multi-drop polling of the Allen-Bradley MicroLogix 1000 PLCs. A MicroLogix 1000 processor (as well as an SLC 5/03 or 5/04) can be used as a Master while Data-Linc LLM1000 and MDL500 half duplex, carrier-controlled FSK wire modems or license-free SRM6000 frequency-hopping spread spectrum radio modems are used for data communications.
For example, special programming enables the MicroLogix 1000 to be uniquely addressed and to control the transmitter carriers on the LLM and MDL series modems. The program mimics a MicroLogix Remote address and creates a pseudo RTS line with RTS send delay for modem carrier control. In keeping with Data-Linc's support of easy installation, the program is available from Data-Linc in diskette form. Therefore, ladder logic does not have to be created from scratch.
Q: Why is this significant?
This development expands the capabilities of the Allen-Bradley MicroLogix 1000 processor. Instead of being able to communicate with just one other MicroLogix unit, the PLC can now communicate with as many remote MicroLogix processors as necessary in an installation, using either Data-Linc's license-free radio modems or FSK wire modems.
Thus the MicroLogix 1000 PLCs can be employed in distributed monitoring and control systems involving small numbers of signals. Since the MicroLogix 1000 processors are less expensive than other PLCs, this translates into cost savings for customers.
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