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sahab
2 Posts |
 Posted - 25 May 2005 : 10:55:34
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In the following thread:
topic.asp?TOPIC_ID=616&SearchTerms=485
It is mentioned, "We reconfigure GPIO14 from its RS-232 use as an input(CTS1) and use it as RS-485 RX_enable; GPIO15 is used as TX_enable." Do GPIO14 and GPIO15 only apply to the GC PLUS board or do they also apply to the VGX board? We could not find the location of GPIO14 and GPIO15 on the VGX board, looking at the manual.
We are having trouble transmitting data through serial port 1 configured as Full Duplex RS-485. We have set the jumpers on the VGX board according to the manual to configure serial port 1 as Full Duplex RS-485 (JP10, JP11, JP12, JP13 jumpered on pins 1-2). The following registry value is also set (for CE builds before late 2004
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[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\Serial]
"RS485"=dword:1
To send data through serial port 1 (RS-485), we are using the "COMTerm.exe" program downloaded from this forum. The test data is being sent through a RS-485 TO RS-232 converter onto a PC serial port. I have a program running on the PC which shows any data coming through the serial port of the PC. Nothing comes through when we send data using COMTerm.exe. When I configure serial port 1 as RS-232, and send data using COMTerm.exe, the data gets to the PC and I can see it through the program listening for data transmissions on the PC. Any feedback is appreciated.
-sahab |
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akidder
1519 Posts |
Posted - 25 May 2005 : 15:09:01
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Thanks for the details. Here are some further ideas:
- Make sure using the right registry key to enable 485 for the build you're using (per topic 616, though it looks like you've seen that post).
- When running COMTERM, you'll have to select RTS handshaking so the RTS/TX_enable line can get set correctly for 485.
- I'll assume that you're hooking up the signals correctly to header J14.
- Finally, have you probed the 485 outputs with an oscilloscope to confirm that it's not your converter or cabling that's the problem? JP13 carries the TX signal from the CPU, and JP12 is the TX_enable/RTS line (the enable signals are described in section 3.3.6 of the VGX user manual).
If you are still having trouble, let us know what build of CE you're using. |
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sahab
2 Posts |
Posted - 26 May 2005 : 12:02:33
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Thanks for the quick response. The Build is "ADS VGX - Build 4.20.10" I am in the process of investigating and trying your suggestions. But How can I tell which Registry value to use for my build? Thanks in advance,
-sahab |
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akidder
1519 Posts |
Posted - 26 May 2005 : 12:41:22
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Build 4.20.10 is about a year old. My recommendation is that you develop with the latest release. Take a look at the VGX CE build revision history (topic 1512) and load the current release.
With the new build, you can use the updated key in topic 616:
[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\Serial]
"SerialMode"=dword:1 ;0=RS232, 1=RS485, 2=RS422 |
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VGX RS-485 RX_enable and TX_enable
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