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#237093 - 09/10/2004 05:49 Serial port on docking sled
ltd
new poster

Registered: 31/07/2002
Posts: 18
Which /dev device is the sled serial port connected to?
I see ttyS0, ttyS1 and ttyS2 are present at boot. All attempts I have made to see the device I have connected have failed dismally. It does not need any DTR/RTS/CTS signals (The PC side of the cable has RTS/CTS/DTR tied to ground. The device is working fine on my laptop.

Also are the RX/TX pins of this port crossed over or not?

Is any special configuration needed to stop the player software trying to use the sled port for anything? I have hijack suppress_notify=1

Help appreciated.

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#237094 - 09/10/2004 07:02 Re: Serial port on docking sled [Re: ltd]
mdavey
enthusiast

Registered: 06/03/2003
Posts: 269
Loc: Wellingborough, UK
Quote:
Which /dev device is the sled serial port connected to?


/dev/ttyS1

Quote:

All attempts I have made to see the device I have connected have failed dismally. It does not need any DTR/RTS/CTS signals (The PC side of the cable has RTS/CTS/DTR tied to ground. The device is working fine on my laptop.



Try installing telnetd from here http://www.trejan.com/projects/empeg/#EMPTELNETD

Then telnetting into the Empeg, killing off the player processes and then talking to the serial port.

Quote:

Also are the RX/TX pins of this port crossed over or not?



The FAQ shows RD on serial port pin 2 and TD on serial port pin 3. Mark Lords dock is wired the same way. ISTR that the car sled has RD on pin 3 and TD on pin 2 - bit I could be wrong about this.

Quote:

Is any special configuration needed to stop the player software trying to use the sled port for anything? I have hijack suppress_notify=1



There is a setting in the Hijack menu. Go into "Serial Port Assignment" and set to "Apps Use Serial Port". This setting only applies when the player is in DC/Car mode - you could use the hijack "Force AD/DC Power Mode" setting to help you investigate.
_________________________
Michael
Ex-owner of stolen empeg #030102741

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#237095 - 09/10/2004 08:35 Re: Serial port on docking sled [Re: mdavey]
ltd
new poster

Registered: 31/07/2002
Posts: 18
Thanks for the info. I believe I have found the reason it is not working. I just tested the sled harness with my multimeter and sure enough:

Sled Pin 8 goes to RS232 Pin 3 (TX)
Sled Pin 9 goes to RS232 Pin 2 (RX)

which is the opposite of what the wiring diagram in the FAQ says.
Perhaps somebody should update it.

This is of course assuming that pin 8 is meant to be RX and pin 9 is meant to be TX, hence the system being designed to be a null modem. Can one of the designers confirm this?


Edited by ltd (09/10/2004 08:37)

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#237096 - 09/10/2004 15:41 Re: Serial port on docking sled [Re: ltd]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31332
Loc: Seattle, WA
Quote:
This is of course assuming that pin 8 is meant to be RX and pin 9 is meant to be TX, hence the system being designed to be a null modem. Can one of the designers confirm this?

RX and TX are swapped on the sled harness so it's the opposite of what's on the player body itself. Player itself requires crossed cable, sled harness requires straight-through cable because they're swapped. Covered here.

Naming the RX and TX lines in a standard way on a serial port is tricky because of the whole null modem situation. Do you name them according to what lines you're connecting to those pins, or according to what those pins do? And even then, those concepts shift depending on which end of the cable you're looking at. Personally I think the nomenclature of the individual pins is kind of arbitrary and you just have to know whether your connecting cable is straight or crossed.
_________________________
Tony Fabris

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#237097 - 10/10/2004 02:10 Re: Serial port on docking sled [Re: tfabris]
Shonky
pooh-bah

Registered: 12/01/2002
Posts: 1985
Loc: Brisbane, Australia
Quote:
Naming the RX and TX lines in a standard way on a serial port is tricky because of the whole null modem situation. Do you name them according to what lines you're connecting to those pins, or according to what those pins do? And even then, those concepts shift depending on which end of the cable you're looking at. Personally I think the nomenclature of the individual pins is kind of arbitrary and you just have to know whether your connecting cable is straight or crossed.


Simple. The pins should be named by what they do on that device not what connects to that device. i.e. data comes out on the TX pin.

I still can't understand why the empeg guys did the sled connector the way they did. See here for what's wrong with their choice in my opinion.
_________________________
Christian
#40104192 120Gb (no longer in my E36 M3, won't fit the E46 M3)

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#237098 - 10/10/2004 02:13 Re: Serial port on docking sled [Re: Shonky]
Daria
carpal tunnel

Registered: 24/01/2002
Posts: 3932
Loc: Providence, RI
I wonder if that's why I sometimes noticed minicom being weird about whether I was online (but still doing the right thing)

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