How to produce a +5V TTL signal on COM port?
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Hi, I am wondering if there is any way to produce a +5V clean TTL signal through COM/RS-232 serial port in C++. I just need to produce a clean +ve spike over the serial port. thanks, -Pavan.
You mean other than putting a power regulator/converter to translate +12 to +5? I have never tried to pull constant power from a COM port and I do not know how much current it can source. A good project site can be found at: http://www.epanorama.net/links/project_interfacing.html[^]. Peace!
-=- James
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See DeleteFXPFiles -
You mean other than putting a power regulator/converter to translate +12 to +5? I have never tried to pull constant power from a COM port and I do not know how much current it can source. A good project site can be found at: http://www.epanorama.net/links/project_interfacing.html[^]. Peace!
-=- James
Please rate this message - let me know if I helped or not! * * *If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFilesTo be clear, I just need to produce a signal which will have a spike (think of it as a trigger) whenever I like. This is fed to another signal recorder which keeps looking at this signal for any trigger (spike) and records it. -Pavan.
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Hi, I am wondering if there is any way to produce a +5V clean TTL signal through COM/RS-232 serial port in C++. I just need to produce a clean +ve spike over the serial port. thanks, -Pavan.
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Have not tried it, but you should be able to open the commport with Handle = CreateFile("Com1",....); then set and clear the DTR line with GetCommState(Handle, &Dcb); Dcb.fDtrControl = DTR_CONTROL_DISABLE; SetCommState(Handle, &Dcb); Dcb.fDtrControl = DTR_CONTROL_ENABLE; SetCommState(Handle, &Dcb); You should be able to use simlar code to toggle the RTS bit
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Have not tried it, but you should be able to open the commport with Handle = CreateFile("Com1",....); then set and clear the DTR line with GetCommState(Handle, &Dcb); Dcb.fDtrControl = DTR_CONTROL_DISABLE; SetCommState(Handle, &Dcb); Dcb.fDtrControl = DTR_CONTROL_ENABLE; SetCommState(Handle, &Dcb); You should be able to use simlar code to toggle the RTS bit
I have tried enabling and disabling DTR and also RTS bit, but couldnt see any spike signal on the Oscilloscope?? I have connected pin 4 and pin 5(ground) for DTR bit to the scope and 7,5 for RTS bit. I didn't see any change in the signal (stays flat at zero all the time). -Pavan
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I have tried enabling and disabling DTR and also RTS bit, but couldnt see any spike signal on the Oscilloscope?? I have connected pin 4 and pin 5(ground) for DTR bit to the scope and 7,5 for RTS bit. I didn't see any change in the signal (stays flat at zero all the time). -Pavan
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Ok, I am getting it. Just played around with the output pins using a LED. The signal goes from -11.6v to +11.6v. Inorder to get a TTL signal, it seems we need to use a voltage converter MAX-232(source:- codeguru forums). Do you know any other way to produce a TTL type signal (0-5v) other than using that converter? I am not sure we can produce without using that, but in case if have any idea lemme know. Thanks for the info, -P.
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Ok, I am getting it. Just played around with the output pins using a LED. The signal goes from -11.6v to +11.6v. Inorder to get a TTL signal, it seems we need to use a voltage converter MAX-232(source:- codeguru forums). Do you know any other way to produce a TTL type signal (0-5v) other than using that converter? I am not sure we can produce without using that, but in case if have any idea lemme know. Thanks for the info, -P.
You can try an NPN transistor... try 10k going into the base, then put a Schottky (like a 1N5817) with the cathode directly on the base and anode connected to ground. Then connect a 4.7k from collector to 5v supplied by you. The RS232 ground would have to tie to your logic ground. The 5v signal should be present on the collector of the transistor.