I’m trying to send DMX (an RS485) based serial lighting control system with xbee modules. Could someone give me an example of what i need to process the DMX before it hits the Xbee Data in.
Thanks.
I have no clue what DMX means.
Is the DMX trying to send a request (or data without a poll?) Is it only sending back to the coordinator? or is it a peer-to-peer system?
This defines how easy or hard it is to ‘prepare’ data for the XBee.
DMX is an RS485 based Serial Control protocol for entertainment lighting.
http://en.wikipedia.org/wiki/DMX512#Protocol
I have a transmitter (Coordinator AT) and a Reciever (Router AT)
I know that I cannot just put RS485 into a Xbee, so what do I convert it to before it hits the Xbee.
I’m not sure you can do DMX over Xbee, because if I understand the page you pointed out, the device needs to send a break at the start of each packet (aka: TX pin held in 0/non-std level artifically long).
So the first DMX would send a break, which would be either ignored by the Xbee or confuse it, then the data. Assuming the Xbee accepts the data and forwards it, how would the remote Xbee know to send a BREAK before the packet?
I think you’d at least ened to use the Programmable XBee so that it can have such logic applied - the need to start every serial TX with a break.
Maybe it’s a bit old topic, but we were able to restart.
I think it must be used sn75176 to this case, and it is connected to the XBee.
What do you think about that?
http://pdf1.alldatasheet.com/datasheet-pdf/view/28608/TI/SN75176.html
SN75176 is fine. That’s quite an old chip, and is likely 5vdc only. www.linear.com likely has a dozen RS-485 chips with various power levels. In my designs I’ve commonly use the Maxim 485 chips like MAX485, MAX490, and they have many others.
You can go to many online suppliers and just search for an RS-485 transceiver with a 3.3vdc supply.
If you can not post a scheme how are you connected?
How do you set xbee?
Sorry, I don’t own a schematic for an Xbee-to-RS-485 circuit which I can release. Perhaps call Digi Xbee module tech support and they might have some hints or even example documents.