Protocols & Communication

Question

How is a Freewave-based Wireless radio configured?

Answer

The 5908 uses a FreeWave spread-spectrum radio core. It is capable of hopping rapidly between many channels in a specified pattern. This allows the unit to minimize interference from other radio equipment and natural sources, as those tend to stay fixed on one frequency. Every radio in a system will use the same hopping pattern, staying locked in communication as long as the signal to noise ratio is sufficient. The radio is available either integrated with a SCADAPack controller or in a stand-alone package which is DIN-rail mountable. It may be ordered in either the 900 MHz or 2.4 GHz frequency bands, depending on the customer's needs.

For more detailed instructions please refer to FreeWave's manual, entitled LUM0002AF FGR User Manual V 6.3.pdf. This manual is also available from FreeWave Technologies on their website at http://www.freewave.com or by calling 1-303-444-3862.

Radio Connections and LED's

Antenna port, on the left side of the case. It uses an industry-standard SMA connector. The connector is small and somewhat delicate. If the antenna is some distance away, requiring heavy coaxial cable, a short jumper of lighter cable is needed to avoid stressing the SMA connector. For protection on this port, a lightning arrestor (eg Poyphaser) is suggested. It is usually placed between the jumper cable and the heavier run of coax cable going to the antenna.

PWR IN is a grey screw-terminal connector. It may be removed by pulling upwards while rocking it left-right. Only the leftmost two terminals are used, pin 1 for and pin 2 for . Power requirements are 12 to 24 volts DC, at a current load of 500mA at 12V or 250mA at 24V while transmitting.

COM is an RS-232 port using an RJ45 connector. It is the primary communication port. Plug one end of the supplied short blue cable into COM, and the other end into the desired port of the SCADAPack. If you don't have this cable, or are connecting your radio to another device, you will need to build a 3 wire null modem cable. Do not use a cable with pin 1 connected (pin 9 on a DB9), as many SCADAPack controllers use that pin to supply +5 volts for other devices. See the following pinout diagram.

COM Port   SCADAPack DB9 (programming, diagnostics)
4 — GND — 4 or 5
5 — RXD — 6 or 3
6 — TXD — 5 or 2

(RJ45 pins are numbered 1 to 8, left to right, when looking at the radio's connector)

DIAG is a second RS-232 port, also using an RJ45 connector. It is used to program the radio and to gather diagnostic information about the system, typically from a laptop computer. A null cable is required to connect to DIAG. (RXD and TXD swapped) A cable may be ordered from Control Microsystems (part 297217) which has an RJ45 male connector on one end and a DB9 female on the other..

There are three status LED's on the radio - CD, TX and CTS. CD is Carrier Detect, meaning that a signal has been detected. TX is Transmit, meaning that the radio is currently sending a message. CTS is Clear To Send, meaning that the modem is ready to accept data from the controller. A chart in FreeWave's manual fully describes the action of these LED's, but the most important combinations are described here.

Radio Condition CD TX CTS
Any Programming Mode Green Off Green
Master Connected to Slave Red/Green Dim Red Flash Red
Master Connected - no data Red Dim Red Off
Master Not connected Red Dim Red Off
Slave Connected to Master Green Dim Red Red
Slave Connected - no data Green Off Red
Slave Not connected Red Off Flash Red

**Note: The TX LED will flicker dimly as data is sent.

Radio Programming Software

There are two ways to program the 5908 (FreeWave) radio. The original method is to use a terminal program such as Hyperterminal. In this case the radio itself generates the menus for a user interface. The new method is to use FreeWave's EZ Config software package. In both cases the programming computer must first be connected to the radio's DIAG port by a null cable.

Hyperterminal

Most computers running Windows should have a copy of Hyperterminal, usually in the Accessories folder. Create a new terminal with the following parameters, ensuring first that you select the correct com port on your programming computer:

19200 bits/sec
8 data bits
No parity
1 stop bit
No Flow Control

Press Shift-U (both keys at the same time). This will open the DIAG port for programming, which will turn both the CD and CTS LED's green. The radio will then send the "MAIN MENU" text.

You may then press a number to go into any of the sub-menus, or (Esc) to exit setup. Be very careful, as it is easy to make a mistake and change something unintentionally. While in any of the sub-menus you may press (Esc) to exit. Escape to the main menu before disconnecting.

Ez Config

The easier way to program a FreeWave radio is to install a copy of Ez Config. It is free, and may be downloaded from http://www.freewave.com/softtools.html. Ez Config is a Windows-based program which allows you to set up a configuration offline, then download it into a radio. You may save the configuration for later use. You may also upload a configuration from a radio, and then save it as a file. This method is much more efficient than using Hyperterminal, and less error-prone as well.

To use Ez Config, first open the program and connect a null cable to the DIAG port. In the upper left of the screen, select the DIAG port, and then choose the com port you are using on your computer. Be aware that Ez Config does not change the LED's to green until it is actually doing a Read From Radio or a Program Radio.

Try doing a Read From Radio to upload whatever configuration is currently in the radio. If the connection is not successful check your cable, Port Settings in Ez Config, and ensure that the port is not in use by other software. Once you have read the radio's configuration, click File, Save Radio File, if you wish to keep a backup copy of the existing setup.

Check each of the four tabs, and see how the radio is configured. Make any necessary changes, then click the Program Radio button. Save your new configuration by clicking File, Save Radio File before you exit from the program.

Radio Configuration

This section will presume that you are using the FreeWave Ez Config software, and have already connected to the radio. For more specific instructions, read FreeWave's LUM0002AF FGR User Manual V 6.3.pdf document. The instructions also presume that you are setting up a point to multipoint system. Even if you are just setting up a link with two radios, use this procedure. It is simpler than the point to point setup. Set all parameters as shown on the screen capture images, unless otherwise noted.

Set Operation Mode tab.

Modem Mode:
Select option (2) - Point to Multipoint Master in the master radio.
Select option (3) - Point to Multipoint Slave in the slave radio
Select option (7) - Point to Multipoint Repeater if using as a repeater

Note: If the unit is to be used as both a repeater and a slave, also turn on Slave/Repeater in Multipoint Parameters. Leave the Ethernet Options turned off.

Set Baud Rate tab.

Baud Rate: Select the baud rate that will be used between the radio and the controller to which it is connected by serial port. This is NOT the over-the-air rate. Each radio may be set to a different rate, so long as it matches the attached device.

Flow Control: Set as required for the COM port connection.

Modbus RTU: Set to 1 if using the Modbus RTU protocol on the COM port.

Transmission Characteristics tab.

Frequency Key: Select a value that will the same for all radios in this system. The Key must be different from that used by other systems in your area.

Transmit Power: Set to 1 for bench testing. May be adjusted depending on the distance between the master and slave. 10 equals full output of 1 watt, and 1 equals 5 milliwatts.

High Noise: May be turned on if the radio will be operating in an environment with high radio noise levels, but this will reduce sensitivity.

Remote LED: Will turn the LED's on or off - leave them on unless in a low-power system.

Multipoint Parameters tab.

Network ID: Must be changed from the default value of 255, and all radios must be the same.

Radio ID: Is an optional tagname for each individual radio.

Repeaters: Set to 0 normally, otherwise set to 1 in all radios if there are any repeaters in the system, providing extra time delays.

Slave/Repeater: Turn on if the radio is in use both as a repeater and a slave. (Must be in mode 7 - Point to Multipoint Repeater)

Subnet ID: If no repeaters are used leave both settings at 0 in Master and F in Slaves. If a repeater is used in the system, put the TX Subnet ID of the Master (0) into RX Subnet ID of the repeater. Choose a unique TX Subnet ID for the repeater, and put it into the RX Subnet ID of all slaves off that repeater. Slaves off repeaters will use a TX Subnet ID of F.

Links

What is a process control system?
Why are process control systems needed?
What is SCADA?
Where are SCADA systems used?
How big or small are SCADA systems?
What is monitoring?
What is a station?
What are master and slave stations?
What is communication?
What languages does the SCADAPack speak?
How is data transferred in a SCADA system?
What devices can the SCADAPack communicate with?
How do I determine if communication is successfully occurring?
What happens if communication fails?
How are communication failures fixed?
How is an MDS-based Wireless radio configured?