RADIO COMMUNICATION

[tharun]

Hi all,

         We use satel radios for calm buoy to control room communication. And the process is working. But we have to show that the system is working properly. we are in a position to show that in the scada screen. If the radio communication fails , how can i show that a error has occured in the communication. How can i be sure that the scada screen is not showing the last good value 

Thanks,

[BevanWeiss]

What SCADA platform are you using?

And how many remote devices are involved?

The standard way using something like Geo SCADA Expert is simply to use the Advanced Modbus Outstation alarming for this.  If the 'outstation' is responding to Modus messages, then it will show as 'Healthy' otherwise it will indicate an error.

Citect has similar Hardware Alarms for Modbus devices.

This is a Schneider-centric forum (at least it's hosted by Schneider, so generally focused on Schneider products) so if you have a non-Schneider SCADA then you're probably better looking on a more product specific forum (for your particular SCADA product) than here.

[tharun]

If the radio communication fails , how can i show that a error has occured in the communication. How can i be sure that the scada screen is not showing the last good value.

[Joel_Weder]

Hello Tharun,

As mentioned by Bevan, we will need to know the name of the SCADA host software you are using before we can respond with any clarity.

[BevanWeiss]

If you display the StateDesc of the Outstation within Geo SCADA Expert then it will display 'Failed', and if you configure an alarm severity against the Outstation then it will report an alarm for that Outstation.

All associated points will show a quality of 'bad' Last Known Value.. and this would normally be displayed in a sub-normal colouring so that operators would recognise the value should not be trusted.

In Citect the value will often be replaced with #BAD (which I personally find annoying... since it doesn't provide any useful knowledge of the system prior to the comms outage).

For other SCADA platforms YMMV

[tharun]

We use intouch wonderware.

[tharun]

Hi,

     How to get communication healthy status from a TRIO ER450 serial port? 

[BevanWeiss]

You can use the Trio Diagnostics protocol to get some level of 'health status' from a Trio ER450 radio.

Unsure if this is supported within Wonderware InTouch, if not, then you may need to investigate a custom connector to get similar data into Wonderware InTouch.

[BevanWeiss]

Wonderware Intouch has a similar capability

https://cdn.logic-control.com/docs/Wonderware/Tech%20Notes/Tech%20Note%20587%20-%20Monitor%20Comm%20...

[Joel_Weder]

It is unlikely that Wonderware would include a Trio diagnostics driver, but possible so I do suggest you look. If not, our Trio TView+ Management Suite software includes a Diagnostic program for polling the health status of radios, including E Series. (also a programmer for the E Series radios) It is a no-cost software package that does not take much processor power, so it can typically run on the same computer as the SCADA Host software (eg Wonderware). 

To download TView:

- go to se.com, and on the top bar make sure you have the Global site selected.

- Open the Products menu, then select Telemetry & Remote SCADA Systems.

- Scroll down to Trio Licensed Radios, then select the Software & Firmware option.

- TView+ is the first software item listed.

To poll an ER450 for diagnostic data you will use the same cable you use to program the radio. After installing TView you will also now have all the Trio radio manuals. In the Start menu, go to Trio Datacom then select the E Series user manual. Page 29 includes a pinout diagram for the System port cable, if you choose to make your own cable. Or you can purchase a cable kit, Schneider Electric part number TBUMCAB-TVIEWCABKT

I have attached a Tech Note which describes how to perform a very basic configuration of an E Series radio, then how to perform diagnostic polling using TView Diagnostics. If your radio is already configured you will not need to perform the first few steps, but do make sure the radio's Diagnostics Setup is correct.

I have also included another document which discusses the Optional Automatic Diagnostics reporting feature. If you don't need that just ignore that Tech Note.

[tharun]

Greetings,

   How to know the signal strength (RSSI) in radio without the software(Tview). We planned to indicate the radio communication healthy/failure status in Wonderware. Kindly guide me as soon as possible

Regards,

Tharun

[Joel_Weder]

With our older (obsolete) ER450 radios you must use the Trio eDiags protocol to query the radio for its diagnostic parameters, such as RSSI. Newer radios such as Q Series will allow use of SNMP (over Ethernet) also.

Software that can use eDiags protocol includes TView Diagnostics (included in TView Management Suite) and Schneider's Ecostruxure Geo SCADA Expert. (used to be called ClearSCADA)  You will have to ask the Wonderware support team if they support Trio eDiags protocol.

Alternately, the protocol is quite simple and some end users have created their own custom driver to poll radios. The attached document (Tech Note 87) explains how to do this.

One other option, though it is not as accurate, is to measure the voltage on pin 9 of serial port B. (pin 5 is ground)  There is a chart in the E Series user manual that provides an approximate conversion between the 1...5 volt signal and RSSI. An analog input of an RTU or PLC could do this.

[tharun]

As per the reply, how to take the generated voltage across pin 9 (0-5V) and pin 5 (signal ground) as analog input to plc. Herewith I have attached the image for your reference. In that -dbm mentioned for stronger and weaker signal . When communication fails, There should be low voltage(Weak RSSI) across pin 9 correct? Voltage generated across pin 9 depends on RSSI am I right?

[Joel_Weder]

Yes, that is correct. Should be possible to add a bit of logic in the local RTU or PLC to trigger an alarm if the measured voltage drops significantly below the average number, or if it drops below (example) perhaps about 1.5 volts. Up to you exactly what level you trigger the alarm at.

[tharun]

Hi Joel ,

            Thanks for your patience and kind replies, by the same pin 9 is it possible that i can use a real time LED indication to show my communication status. if so how can i do that? (we want to see the communication status without the use of a laptop/pc) ..

Thanks , 

[Joel_Weder · Accepted solution]

To view the output from the RSSI pin (pin 9 of the serial port) requires a voltmeter of some type. That can be an analog input of an RTU or PLC, or a typical multimeter, or some specialized device. We do not offer such a device, though I have seen them. Eg a comparator IC that turns on succeeding outputs to drive LED's as the voltage rises. But any such device would have to be purchased elsewhere, or custom built.

A preferred alternative is to have the local RTU or PLC measure the voltage and convert it to an approximate RSSI level in dBm. Then a low-cost local display such as a Magelis HMI could poll the RTU (using Modbus) for the value and display it.