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Few questions about PLC modems

Sergey Moshkovskiy
Prodigy 30 points

Other Parts Discussed in Thread: TMS320F28PLC84

Project - PLC modem based on TMS320F28PLC84PNT, AFE031AIRGZR.
Net organisation is G3 Cenelec one master - many slaves. Master sends request, slaves reply.

1. In automatic mode modems self-determine the routes from master to slaves and vice versa. It takes up a lot of time, and this settings are lost when power is down.
Is it possible to save this setting somewhere in slaves and master memory to achive fast start?

2. Is it possible that this settings store in 24C1024 which is mentioned in reference guide, but not exist on demo-boards?

3. Is it possible to initialize modem with DBPSK modulation and then reconfigure it to more fast settings - even up to D8PSK - in case of good communication conditions?
Or modem do this automatically (switches to high speed settings in case of good communication conditions and switches back to low speed in case of noice environment).

4. Is it possible to build the network with 2000 nodes since joining process with 30 nodes takes up to 15 – 60 minutes (like it is mentioned in FAQ)? Or just not possible because lack of time?
http://processors.wiki.ti.com/index.php/Smart_Grid_PLC_FAQ#G3

5. Is it possible to build several independent subnet with different frequency band in one network? ( each subnet has own fixed frequency band).

6. If the modem has a power supply without galvanic isolation, could it be possible to use it without communication transformer? Does TI have a transformerless PLC reference design, can we get it?

  • 0
    TI__Expert 8635 points

    Hi Sergey,

    I tried to answer some of your questions. My colleagues may please correct me if I’m mistaken on some of the points.

    1. The data concentrator generally stores its information in the RAM memory. A backup of the current network alignment is, as far as I know, not made in a non volatile memory.

    2. What features are you referring to?

    3. You will need to define the modulation from the host processor so it is possible to change it. For my understanding you cannot decide this in an established network because you will lose the connection to the DC since both, modem and DC need to use the same modulation.

    The modulation can be defined in an automated adaptive process. The chosen modulation will be communicated to the DC via the TMR (Tone Map Response) message.

     

    4. I don’t know exactly the maximum number of nodes. At least 256 should be possible. With 2000 nodes there may just be too much traffic on the line for a reasonable communication.

    5. You are able to freely define the tone mask for the chosen band so you may be able to separate the transmission band from different networks on the line. I would doubt that this has advantages for the transmission.

    6. We don’t have a reference design for this. I cannot comment if it would be possible.

  • 0 in reply to Simon Jagla
    Prodigy 30 points
    1. Is there any possibility to make a reserve copy in nonvolatile memory? Are there any commands for TMS320F28PLC84 to write network configuration from RAM to EEPROM and back?
    2. What purpose for EEPROM -U2 AT24C1024 on testing board TIDM-SOMPLC-G3? We suppose it is installed for the purpose described in question one, right? Is that possible to use 24C512 instead of U2 AT24C1024?
    4. Please give some examples of network discover time with nodes close to 1000 units. 
     
    One more thing. What purpose for DNP components (R33, R34, C55) on TIDM-SOMPLC-G3 connected to the port ADCINA0/VREFHI  TMS320F28PLC84?