asio: serial ports and timeouts
Hi again
I was playing around with asio a bit, creating the following class:
AsioPlayground::AsioPlayground() :
maxCharDelay(seconds(10)), charTimeout(io, maxCharDelay), port(io,
"COM2") {
port.set_option(serial_port_base::baud_rate(9600));
port.set_option(serial_port_base::character_size(7));
port.set_option(serial_port_base::flow_control(serial_port_base::flow_control::none));
port.set_option(serial_port_base::parity(serial_port_base::parity::even));
port.set_option(serial_port_base::stop_bits(serial_port_base::stop_bits::one));
}
AsioPlayground::~AsioPlayground() {
}
template<>
void AsioPlayground::write<string>(const string &value) {
boost::asio::write(port, buffer(value, value.size()));
}
template<>
void AsioPlayground::write<char>(const char &c) {
boost::asio::write(port, buffer(&c, 1));
}
template<>
char AsioPlayground::read<char>() {
function
However, if I transmit 9 characters from the device, these characters are displayed, appended by a '\0' character (or whichever character I choose as default in read<char>()).
io.run() seems to return immediately, not even waiting for any characters to be transmitted.
Could you clarify the above 2 sentences? If these characters are displayed, they have been received, right?
Well, if I transmit 9 characters (or less, whatever), e.g. "012345678", these characters are displayed, followed by a '\0'. Transmitting only 6 characters displays these 6 characters, e.g. "012345" and 4 appended '\0' characters. That's not what I want, I want the program to block and wait for the 10th character in the first example or the 7th, 8th, 9th and 10th character in the second example. Igor R wrote:
However, if I transmit 9 characters from the device, these characters are displayed, appended by a '\0' character (or whichever character I choose as default in read<char>()).
io.run() seems to return immediately, not even waiting for any characters to be transmitted.
Could you clarify the above 2 sentences? If these characters are displayed, they have been received, right?
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Well, if I transmit 9 characters (or less, whatever), e.g. "012345678", these characters are displayed, followed by a '\0'.
Transmitting only 6 characters displays these 6 characters, e.g. "012345" and 4 appended '\0' characters. That's not what I want, I want the program to block and wait for the 10th character in the first example or the 7th, 8th, 9th and 10th character in the second example.
Ok, I see... I don't really understand why you wish to async_read() char-by-char and to re-run io_service each time, instead of reading N chars at once into a buffer, but if you prefer to do so, you have to call io_service::reset() before any subsequent call to run(): //... io.reset(); io.run(); //....
Thanks, man, that was the problem :-) . I do read them char-by-char because I need to specify the maximum delay between each character using async_wait(). If I read all 10 characters at once, I could only specify the maximum time for the transmission of all characters, not the allowed delay between each one. The protocol I am implementing strictly relies on a maximum character delay between each subsequent character. Thanks and greeets Pascal Igor R wrote:
Well, if I transmit 9 characters (or less, whatever), e.g. "012345678", these characters are displayed, followed by a '\0'.
Transmitting only 6 characters displays these 6 characters, e.g. "012345" and 4 appended '\0' characters. That's not what I want, I want the program to block and wait for the 10th character in the first example or the 7th, 8th, 9th and 10th character in the second example.
Ok, I see... I don't really understand why you wish to async_read() char-by-char and to re-run io_service each time, instead of reading N chars at once into a buffer, but if you prefer to do so, you have to call io_service::reset() before any subsequent call to run(): //... io.reset();
io.run(); //....
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