All data coming to the serial port in linux is stored in the files. Therefore, it is necessary to check the file with a certain frequency. You can use a for-loop to do this.Your mistake is that you send data and try to get it on the same port.
And this is not possible.
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/dev/port is a kind of 'pseudo-file' which uses the same semantics for reading and writing as does a normal file: open/read/write/seek/close. You open the file '/dev/port', just like an ordinary file. To access a particular IO port, you seek to that port, as if you were seeking to a particular byte offset in a normal file.
All subsequent reads or writes will get/send the data to/from that IO port. You can then seek to a different port address, for read and writes there.If you find this difficult, I think you will find the parapin interface equally challenging. For any of this to make sense, you need understand the fundamental basis of accessing IO space on an x86 CPU. Have you done any prior programming at this level on any platform?
There is a decent discussion of the concept in, where I posted some C code that demonstrates the concepts.- rod. Didn't mean to step on any toes as it were. But I've been researching the topic about an hour now. And read through the above topic as part of that research.
Upon hitting the bottom of the thread, the answer was not conclusive.I figured that i would save someone else the trouble and post the detailed information here. Rather than start a mirror thread.
I'm quite active on the LinuxCNC forum. And I have seen up to 5 threads following the same issue. I always attempt to mitigate that.
Ps/2 Port
For example, I had a thread about. And when resolved, had another thread about. In the body of each thread, I supplied a link to the parent thread so that any user could gain from what had been learned without excessive searching.Anyway, assume positive intent.:-)Once I get a handle on Linux programming. I'm sure I'll be full of questions.Thanks,Jerry. @AskJerry: Your experience and skills are a welcome addition to LQ!However, as you mentioned in order to be able to post a link to your own site or other arena where you participate, I think it important to comment:Although there must be rules in a public forum, LinuxQuestions is not about 'the rules', it is all about participation, sharing and interacting with others, helping others and forming a community in the process. As such, the rules are there as a guide, not an algorithmic device to be used for advantage.Posting self-contained, complete and relevant replies to the questions of others, even in older threads, is always welcome! Seeking out old threads as an opportunity to post self promoting links, relevant or not, is not acceptable behavior.Please remember that your posts here form a permanent resource which will be found by others seeking help for years to come.
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