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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