Troubleshooting RS485

[rthorntn]

Hello most helpful peeps,

What would be the best portable way to see the data on my inverter and chlorinator rs485 ports, both are outdoors and I haven't had much luck getting the inverter working with the vendor software, it would be cool to see the rs485 packets on a tablet (have Win7 and Android tablets)?

Thanks.

Richard

[lapm]

Well depending on speed you might be able to use rs-485 to rs-232 converter with terminal program to capture it...

[digsys]

RS485 to RS232 conversion is very simple and easy. Do you have an RS232 port? If so, there are many ICs to convert RS485
to TTL first. If you're just peeking at the data, you don't need to do the extra TTL to RS232. I use 300R series resistors on
RXD and TXD, and a 5V1 zener on RXD. I have heaps of converters if you get stuck.

[rthorntn]

Thanks peeps, I checked my "inventory" which nowadays consists of searching my Gmail for it and found a ftdi usb-rs485-we-1800-bt I got from Element14, I use rs232 a bit to configure network equipment, is there a Linux/Mac or Windows app that I could use, does rs485 have a baud and start/stop/parity?

EDIT: so rs485 is the PHY, so does anyone have any idea if aurora inverters and zodiac chlorinators use modbus over rs485 then?

[tszaboo]

RS485 101:
Did you put there the termination resistors? Measure resistance between A and B.
202: Put two, anti-parallel LED and a sized resistor between the A and B. Are both of them lit, when you send data?
Then use the big guns, only after this.

[mikeselectricstuff]

You may get away with just connecting D- to an RS232 input.
What is harder to tell is which direction data is going at any time - one way to do this is tap into it before the transceivers.
Another is to use a scope, and if necessary add some series resistance, so each end will show  a slightly different voltage level   on the scope

[Macbeth]

I did this years ago using a Maxim MAX485 instead of the usual MAX232 type devices. I got it as a free sample too!

[rthorntn]

Thanks everyone, so the FTDI RS485 to USB adapter I have, what would you all try with it?

I have the aurora solar inverter and a zodiac chlorinator, do most of these things use MODBUS?

I have a Rigol scope and an Agilent DMM if that would help in my quest.

Update: power one aurora seems to use a proprietary protocol:
http://stephanos.io/archives/96

Update 2: zodiac seems to use a proprietary protocol also:
http://www.troublefreepool.com/control-your-jandy-equipment-from-your-pc-with-a-15-adapter-t28409-200.html#p606529