[Imported] Diagnostics thru back-to-back repeater not working

[sbeadle]

>>Message imported from previous forum - Category:Trio Data Radios<<
User: joelw, originally posted: 2018-10-17 21:08:45 Id:106
This is a re-posting from the obsoleted (October 2018) "Schneider Electric Telemetry & SCADA" forum.

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VirgilNicklas
**_Hello, I have been working with Trio PADs [data radios] for a few months. Their use of streams comes in handy when one needs not to only pass data but also be able to monitor the RF network. I have an MR450 connected (via 232) to a server. This radio connects via RF to an ER450 which has another MR450 connected to its port 1 as well as an RTU on port 2._**

**_The server's radio has opposing freqs to the ER450 repeater unit. The MR450 on the repeater unit has a linking freq, which exchanges data with another site that has pretty much the same layout as the one I just described. Only difference is the outstation radio is connected to a PLC. After setting up the streaming of all the units in the network, the data managed to come through and the diagnostics for the area that is serviced by the repeater serving the server. However, the diagnostics through to the other area does not work. Is there something I am leaving out?_**

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jweder:
If you are having immediate problems, please contact our Tech Support team directly. This forum is not designed to provide quick responses. You can call them at 1-888-226-6876 or email them at SupportTRSS[at]schneider-electric.com.

Speaking generally though, what you are talking about here is called a back-to-back repeater, or a tail-end link. It consists of two pairs of radios, each pair operating on its own network, on a unique radio frequency (or pair of frequencies). This will work fine, as long as you manage possible interference issues at the repeater site. This requires:
- Significant frequency separation between the two systems eg 5 MHz AND
- Significant antenna separation eg one directly above the other by about 6 metres OR
- If a duplexer (3 port mechanical filter) is purchased and properly tuned, you can connect both radios to a single antenna.

If each radio network is operating properly, and then you connect user data ports of the two radios at the repeater site together with a 3 wire NULL (cross-over) modem cable, you will get user protocol data out at the Outstation. However, diagnostic data is different...

Diagnostic data is typically routed to each radio's internal processor when the configured Stream ID is seen on an incoming data packet. (typically 0) In the case of a back-to-back repeater we also want the diagnostic data to go between radios so it gets onto the second radio network. This data can NOT use the user data port, as the configured Stream ID is not correct.

Instead what you need to do is connect the System (programming & diagnostics) port of the two radios at the repeater site together. This requires a NULL cable, similar to the cable for the user protocol data. You must make a cable, as Schneider/Trio does not have one for sale. The user manual lists the System port pins.

**Radio 1____ Radio 2**
RxD ----- TxD
TxD