where is the "DB9_+12V" on the emeter board(EVM430-F6779) from??

Sanzheng Yin

Hi, i am now learning the emeter board EVM430-F6779(EVM430-F6779 ,one 3 Phase Electronic Watt-Hour EVM for Metering from TI).

When reading the doc slaa577g.pdf I was coufused with the "Isolated RS232 Communication"part(pls refer Figure 34,page 40 of slaa577g.pdf),because

i really dont know where the "DB9_+12V" is from????

I know this "DB9_+12V" powers the isolated rs232 to communicate with other device,but the doc slaa577g.pdf dont tell us where this 12v voltage is from,and also i referred the schematic document tidr376.pdf,i still found i am confused.

over 9 years ago

0 Dennis Eichmann over 9 years ago

Guru 74080 points

Hi Sanzheng!

Both voltages, DB9 +12V and DB9 -12V come from the PC side. These are the signal levels of a RS-232 connector. As you can see from the schematic, beside from pin 2 and 3 which are used for transmitting data, also pin 4 and pin 7 (DTR and RTS) are used, but only to power the isolated RS232 communication. This means you will not find any other node in the schematic with those names because these voltages come through the DB9 connector.

Dennis

0 Sanzheng Yin over 9 years ago in reply to Dennis Eichmann

Prodigy 80 points

thanks a lot!

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where is the "DB9_+12V" on the emeter board(EVM430-F6779) from??