Raymarine Output Problems

[labatt]

Correct me if I'm wrong, but while the standard allows for multiple talkers it can only be done via a multiplexer... the multiplexer will act as a hub, aggregate the inbound datastreams and then output them to as many listeners as the multiplexer can support. Now I have to go do some research to verify this... I can't see how a serial connection could have more than one device outputting at one time though... Since it's really just a series of electrical impulses and there is no collision control on serial, it would just seem like a mess to any listening devices, wouldn't it?

[brak]

Indeed, one transmitter - one wire. But you can connect more than one listener to that same wire, as long as there is enough power in there to drive them. Probably not the optimal way to do things, though.

Now I do wonder how they deal with that in Seatalk. It runs an actual bus over 2 wires (with multiple talkers and all).

Originally Posted by labatt

Correct me if I'm wrong, but while the standard allows for multiple talkers it can only be done via a multiplexer... the multiplexer will act as a hub, aggregate the inbound datastreams and then output them to as many listeners as the multiplexer can support. Now I have to go do some research to verify this... I can't see how a serial connection could have more than one device outputting at one time though... Since it's really just a series of electrical impulses and there is no collision control on serial, it would just seem like a mess to any listening devices, wouldn't it?

[brak]

Found it - http://www.thomasknauf.de/rap/seatalk1.htm, wow - thats a sweet protocol.

[labatt]

Originally Posted by brak

Indeed, one transmitter - one wire. But you can connect more than one listener to that same wire, as long as there is enough power in there to drive them. Probably not the optimal way to do things, though.

Now I do wonder how they deal with that in Seatalk. It runs an actual bus over 2 wires (with multiple talkers and all).

Collision control - something that doesn't exist within the NMEA 0183 standards but does exist on the 2000 standards. With regards to putting multiple listeners on the same wire, I'd probably hesitate to do that. Unless you are really good at crimping and creating taps, a single additional listener could cause a large voltage drop and then NONE of your devices would work. I'd lean heavily towards an active multiplexer. I hate tracing electrical gremlins.

[labatt]

Just got an e-mail from Maptech... the problem is indeed a bug and will be fixed in the next release (who knows when that will be).

[sailingdog]

Don't hold your breath...

Originally Posted by labatt

Just got an e-mail from Maptech... the problem is indeed a bug and will be fixed in the next release (who knows when that will be).