  |
Bentek Systems SCADA & Telemetry Solutions |
|
Home ProductsServicesApplicationsContact Us
|
Cellular SCADAWhen should Cellular Data Networks be considered for SCADA applications?
Use of Cellular technologies for SCADA may be considered when wide area coverage is required and the cost of alternative technologies (Private Radio systems, Satellite, etc...) is uneconomical.
Although Cellular communications is available throughout many parts of North America and many remote sites are covered by Cellular, there are still many areas where it is not available due to remoteness and lack of customer base. When considering the Cellular SCADA communications option, check with your local Celllular Provider to see if Cellular data service is available in your area. Cellular communications may be employed as the link to all remote sites or as a main link to a hub site, with private radio system used to extend out to nearby sites.
What technologies are available for SCADA communications over Cellular?
Technologies for SCADA communications over cellular include:
Circuit Switched data is essentially dialup modem communications except that instead of a normal landline, it is performed over a cellular phone network. Cost is based on connect time. A disadvantage of Circuit Switched data connection is the delay time to establish connection. It is therefore not suitable for bursty traffic where there is frequent connection required. Because Circuit Switched data services are billed by time, it is suitable when there is infrequent connection and large data files are transferred at high speed.
Packet data is characterized by an “always on IP connection". Packet data service is billed by Kilobyte transferred rather than by time. Since the connection is always maintained, it doesn't have the connection delay overhead associated with circuit switched data service. Packet data service is therefore suitiable for bursty traffic with small data files transferred. Packet data service is suitable for common SCADA & Telemetry applications like data collection or alarming because small amounts of data are involved and remote systems often monitor 24/7.
Other advantages of packet data is the routable IP connections and the rapid transmit time.
What are the Advantages and Disadvantages of Cellular Data Networks?
Advantages of utilizing Cellular Data Networks:
there may be lower capital costs since coverage provided by the existing cellular infrastructure may reduce or altogether eliminate the need to erect large telecommunication towers.
when packet data Cellular Data is used, it enables IP host connection enabling a normal desktop PC to access the remotely connected equipment.
Disadvantage of Cellular Data network:
there may be no coverage available
ongoing cost, and packet-based billing may limit the amount of data that can be economically transferred.
Costs
There is monthly airtime costs for use of the cellular data network.
Monthly Circuit Switch data cost consists of a fixed airtime charge, and an additional airtime charge typically ranging from $0.10 to 0.50 $USD per minute. Long distance charges are additional if applicable.
Monthly Packet data cost is charged by Kilobytes transferred. Cellular providers have different plans (which could range from a set minimum to an "unlimited" maximum); each consisting of a minimum block of Kilobytes. If the monthly Kilobytes transferred figure is exceeded, the balance is billed as extra charges. Site costs typically range from $30-$70 per month (including the Kilobyte transfer).
Coverage
Although Cellular communications is available throughout many parts of North America and many remote sites are covered by cellular, there are remote areas where coverage is not available. Check with your cellular provider for available data services.
Types of Cellular Data Services
Best use of Cellular Data Technology
Because of the pricing structure of Cellular data services,
SCADA over Cellular networks is optimized for SCADA applications that require periodical data retrieval such as daily reports, or change of state reports such as Alarming.
and not optimized for Data Acquisition applications that require high speed and/or large amounts of data transfer. These may be better served by private radio networks.
Cellular SCADA vs. Cellular Telemetry
There are both SCADA and Telemetry solutions over Cellular networks today. What criteria is used to select which technology is best for an application? The primary factor determining this is the quantity of I/O involved in the application. If there is just a small number of I/O between 2 sites, then Cellular Telemetry products are a better and more cost-effective solution. If there is a large number of I/O and multiple sites, then Cellular SCADA is a better solution.
Below is a diagram of how an enterprise-wide IP-based SCADA system can be implemented using Bentek System's UNICON IP RTU/Modem for SCADA communications over the cellular infrastructure. A large enterprise may have a variety of different types of remote assets and existing communication systems. The cellular infrastructure can serve as a backbone to integrate and enable communications from SCADA Hosts in the office with remote field assets including:
|
|
spectrum |
|
Bentek Systems SCADA & Telemetry Solutions |
504 - 42nd Ave.S.E. |