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Use Com port to control relay card

Question asked by douba on May 15, 2019
Latest reply on May 21, 2019 by douba

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Hello,

Here I want to control a relay board with COM port(RS 232), its switch on command is "01 05 00 00 FF 00 8C 3A",

At the beginning, I use a COM debug application(XCOM V2.0) to try the connection, and it is working properly.

see below picture,

Then I try to use the "Direct I/O" to control the relay board, the problem is no response!

please see below picture, and I double checked the serial port setting, it is correct.

how should I do next step? thanks a lot!

BTW, both "EOL OFF" and "EOL ON" were tried, but didn't work.

Regards,

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Stan Bischof May 15, 2019 8:59 AM
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Likely handshaking setting or EOL. Not just EOL ON/OFF, but what EOL char(s) are needed. Check the relay docs and see what they require. COM ports work fine but are very particular- everything has to be just right.

Stan
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- Stan Bischof @ Stan Bischof on May 15, 2019 8:59 AM
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  PS- if that doesn't help, try asking in VRF- lots of experience there.
  
  Stan
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emcpete May 16, 2019 6:11 AM
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Here's the way that I control this relay. First open "GuiApp_English". Select "Find device". The address of the relay card will be identified. Take note of this address. When you open the device you should be able to control the relay. Close the "USB Relay Manager"

From VEE:

I placed the executable "USBRelay.exe" in the vee folder. The OP0TV is the relay address.
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- douba @ emcpete on May 21, 2019 4:37 AM
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  Thank you very much!
  I understand this is a way to get control it.
  But this switch box don't have any driver, so I have to use the COM command directly.
  
  Regards,
  
  Qi
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Stan Bischof May 17, 2019 11:02 AM
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Oops. No idea why I didn't notice something so obvious, but---- in your DIO you are are entering TEXT values and since you are choosing HEX Formatting are expecting the text to be interpreted/sent as HEX values. Well- that's not going to happen- text is sent as text- the HEX formatting does nothing, just like in virtually any language. Convert your input to numerics and you'll maybe be more successful.

At the same time, if you indeed have device drivers as Peter's example notes, then that would indeed be a good alternative to sussing out the communication details.

Stan
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- douba @ Stan Bischof on May 21, 2019 4:34 AM
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  Hi Stan,
  
  You all right! thank you very much!
  Now I convert the command from HEX to DEC, and use the "write byte" transaction, it is working now,see below picture.
  Regards,
  Qi
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Use Com port to control relay card

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