Wireless Transmitters – Advantages, requirements and uses

At RealTech Controls we provide the highest quality brands and customized systems for industrial process instrumentation and control equipment.

One of the major growth areas we see occurring across multiple industries is the need for reliable wireless communication. This saves costs by reducing or in most cases eliminating the need for digging trenches for cabling, running conduit, and the additional support structures involved as well as other hidden costs.

We find this need has increased in the past few years, due to the progress of the wireless technology whereas some years ago radio signals were found to be somewhat unreliable and signal loss could be intermittent, causing downtime and increased maintenance.

Today’s modern wireless technology is reliable, with systems normally capable of indicating the strength and status of the wireless signal along with redundancy to provide a stable, secure connection of point to point, or point to multi-point communication.

Wireless security concerns addressed

Along with wireless technology comes the concern with security, especially in the current economic climate. Most companies we find have two separate departments for Instrumentation/Control, and then IT. Some IT departments implement a zero-tolerance policy for the incorporation of external wireless radios, especially in the water treatment, and Oil and Gas industries for obvious reasons. These two departments often have different roles when it comes to the operation of a plant or process – For example: The I&C side strives to simplify the process, decreasing maintenance and thereby achieving cost savings and reduced labor. The IT side strives to achieve network security, provide different access levels, streamline the SCADA system and so on.

From a technology standpoint, these two objectives could conflict with each other, whereas simplifying the process by using wireless devices, may increase the security risk etc.

 

However, another challenge we have encountered in the industry, is the learning curve for the different departments to understand the way particular wireless devices operate. We find that once this is generally explained in detail with all questions and concerns addressed, projects move ahead smoothly. This can be explained as follows:

 

RealTech Controls distributes the Analynk Wireless radios that use the 900Mhz frequency range for our systems as they do not require any licenses, and have excellent line of site transmission. Although many systems are used were line of site is not possible as well as numerous obstacles being present, the signal can then simply be verified by the on-board RSSI (received signal strength indication), to ensure reliable, consistent and stable transmission.

Our wireless technology uses secure spread spectrum transmission, where the data is constantly hopping frequency bands, and with 256 bit encryption makes it virtually impossible to break into. Adding to this, the data is point to point, not on a network which generally calms IT concerns, and is not available to the general administration running of the facility.

This data, usually in the form of mA and Digital signals, or Modbus RTU is often then sent from the receiver radio directly into the existing SCADA or PLC, where security is already in place, as per the normal running of the facility.

 

Compatibility / Systems

Another conversation which often comes up with customer applications is the compatibility with devices to communicate with each other, as well as the already installed on-site PLC and SCADA systems.

RealTech Controls provides the Aparian and PR Electronics range of communication routers, and signal conditioning and converter stand-alone modules. These devices are completely compatible with each other, as well as the majority of existing on-site instrumentation.

 

Most industrial control signals coming from field transmitters are majority mA (could be HART), Volts, Temperature (RTD and TC), Frequency, Dry Contact Switch, or in some cases serial communications (Modbus – RS232/485) etc. It is usually very expensive to have the SCADA / PLC’s installed with input cards to accommodate all these different types of inputs, and so it is common to standardize for example on either mA or some type of communication like Ethernet/IP. It is therefore necessary to convert field signals into these standard input types, and so the signal routers and conditioning devices come in handy.

Typical Example

A water tank is required to maintain a Chlorine level to 0.6ppm, and the control verified by a control room located a mile away with input into a Rockwell PLC using Ethernet/IP.

RealTech Control provides a system consisting of the EMEC range of water treatment analyzers and dosing pumps, the Analynk Wireless transmitters, and the Aparian Router to convert the received mA signal into Ethernet/IP.