USB RS485 reads only junk

[dirkaw]

Hi there!

I have a Jandy PDA8 controller that has a Jandy RS485 multiplexer. Initially it had the salt water cell and the PDA box connected to it. I disconnected the PDA boxes' RS485 cables and connected the FTDI RS485 USB adapter to it. The connections I made are:

• FTDI orange: Data+ (B) - CONNECT to RS panel Pin Hardware connection #2 (black)
• FTDI yellow: Data- (A) - CONNECT to RS panel Pin One Touch #3 (yellow)

dmesg reports the RS485 adapter as ttyUSB0. When I run the sudo -s eval 'stty raw -echo < /dev/ttyUSB0; cat -vte /dev/ttyUSB0' command I'm only getting "junk".

So I'm wondering if the wiring is wrong. Do I need ground or short the FTDI RS485 adapter's termination wires?

Also what would be upgrade options? The board is 8124A. I assume I could buy

1. a RS8 PPD chip for around $180 or
2. an entire power center assembly for $500+

Thanks!

[sfeakes]

depending on what you have connected to the RS485 bus, you may only see junk on a PDA panel, so try running serial_logger with and see if you get any results.
If not, Try swapping Data+ and Data- over. It won't harm anything if you get those two round the wrong way, and it's a common mistake to make.

#1 If you can still find the RS chips, that's an option. But you will be limited on the Rev# you can support with the chip.
#2 They shouldn't be that much. I recently got a RS8 Rev T.2 for about $200 off eBay.

[dirkaw]

Thanks for your response!
I tried swapping Data+ and Data- and that gives me just different junk.
I also tried connecting GND and terminating the bus with the green+brown wires from the FTDI USB2RS485. And also connecting directly without the multiplexer. None of those helped.

Are you saying with the PDA board it wouldn't report temperature data? I need to try again with serial logger I forgot to stop aqualinkd.

Was your RS8 Rev T.2 for about $200 off eBay for just the CPU board or the entire power board with CPU? The cheapest power board with a recent software is $500. Maybe it is seasonal when pool stuff gets replaced in summer. I'll keep an eye out.

Thanks!