A major problem that often comes up in industrial automation, particularly when trying to upgrade existing systems, is simply finding a way to get a process signal from point A to point B.
Running physical wires between devices can be costly and time consuming, especially when there is a need to run them through conduit or dig trenches. Facilities that have been in operation for a long time may have gone through many iterations of process control equipment, leaving behind a rat's nest of old wires which make running of new wires nearly impossible. Certain applications can even prohibit the use of physical wires entirely, such as filling stations at shipping docks and truck terminals where the transmitter is located on the vessel or vehicle.
Going wireless can be a good alternative in these scenarios, but upgrading older systems to communicate over ethernet can be equally expensive, not to mention incredibly complex. Buying entirely new transmitters that include wireless technology can be an alternative, but they too can be prohibitively expensive.
Going wireless can be a good alternative in these scenarios, but upgrading older systems to communicate over ethernet can be equally expensive, not to mention incredibly complex. Buying entirely new transmitters that include wireless technology can be an alternative, but they too can be prohibitively expensive.
Precision Digital's PDW series of industrial wireless solutions provide a straightforward way to transmit existing 4-20 mA,
0-10 V, discrete digital signals, and Modbus® serial communications wirelessly, without the need to first convert them into digital TCP/IP or UDP protocol signals. This allows them to be easily installed into all kinds of existing systems while avoiding installation headaches.
PDW Wireless Products
Precision Digital's PDW30 is a point-to-point wireless process signal bridge, perfect for connecting two field locations together. It consists of a primary and secondary wireless unit which accept an analog signal (4-20 mA, 0-10 V, 0-5 V, 1-5 V), up to four discrete digital input signals, and Modbus serial communications. They can then output a 4-20 mA signal, up to four discrete digital outputs, and Modbus at the other end. Communication between the devices is two-way, so each wireless device can input and output at the same time.
The PDW90 Point-to-Multipoint Wireless Process Signal System is a solution for more complex wireless applications where process signals from multiple field locations need to be consolidated in one central location, such as a control room or central monitoring location. In order to be as flexible as possible, the PDW90 base station has completely modular inputs and outputs, including analog in, 4-20 mA out, discrete digital I/O, mechanical relays, and Modbus serial communications. Up to 32 individual field units can be placed at different locations around a facility 2 and connected to a single base station.PDW Wireless Accessories
Precision Digital's line of industrial wireless products also includes accessories to expand and customize an installation to meet the unique needs of any application. Wireless installations may be expanded using an array of base station modules, additional wireless field units, repeater units, and high-gain antennae for longer distances. The wireless survey tool kit can provide an accurate representation of wireless signal strength throughout your facility before performing the installation. PDW products have a signal range of 1 mile line-of-sight outdoor or 500 ft. indoor.
This range can be expanded using wireless repeater units or high-gain antennae. PDW products include free PDW Manager PC programming software.
PDW90 Wireless System Typical Setup
Applications
There are many process control applications
where PDW wireless products could prove to be the cost-effective and efficient solution. Custody transfer terminals, for instance, could use PDW wireless systems to remotely connect to transmitters located on shipping vessels to gauge product levels and flow rates. PDW90 wireless field units located on the vessel can be programmed to connect to the PDW90 base station when the vessel comes into port. This eliminates the need for workers on the vessel to manually gauge these values and radio them into the station, or for any additional systems to be setup on the vessel once it's in port.
New safety and efficiency regulations often come up in the process control industry, and some of these can require the installation of new equipment. Running wires through existing systems can often be a nightmare. Existing wires may run through conduit which new wires will need to be snaked though and it may even be buried underground in a trench requiring excavation. Connecting the PDW30 units to a new device and allowing the signals to be communicated wirelessly takes a fraction of the time.When it comes to purchasing transmitters and sensors for new installations, purchasing less expensive wired transmitters and pairing them with PDW wireless products can actually be less expensive than purchasing an all-in-one wireless transmitter that does the same thing. This can often constitute a significant cost savings.
Summary
Going wireless can be a solution to many common installation problems that come up when retrofitting existing process control systems, but it can also create headaches of its own. Many common wireless solutions on the market require that process signals be converted to ethernet protocol or make it necessary to repurchase the entire system at greater cost. Precision Digital's PDW industrial wireless systems are designed to hook directly into an existing process control
system and transmit many common process control signals, such as 4-20 mA, discrete digital I/O, and Modbus, wirelessly from point A to point B. With Precision Digital's industrial wireless products, going wireless doesn't have to break the bank, or your existing systems.
For more information on Precision Digital's PDW
wireless products visit predig.com/wirelessproducts
by Simon Paonessa - Technical Writer,
Precision Digital Corporation