#Serial port serial
The embedded code was compiled into an executable for the test platform - using a custom runner script and a mock serial API which read from and wrote to stdin and stdout. This virtual serial port was configured to pipe all data transferred to an executable (using stdin and stdout).
![serial port serial port](https://image.slidesharecdn.com/aslides-160906131939/95/a-certification-core-hardware-pc-maintenance-41-638.jpg)
Using the tool, I could create a virtual serial port in the test environment.
#Serial port how to
Thinking about how to handle this, I eventually settled on a neat solution using the socat utility. This came with the challenge that the test environment would not have the device connected to the serial port.
#Serial port series
As part of the development, there was a series of system tests which ran from the development machine, sending example commands to the device and then checking the responses against expected values.Īs part of the testing process, I wanted to run the system tests in the CI/CD pipeline. Application commands and device responses were exchanged using the device’s serial port. Recently, I’ve been working on an embedded system which used a physical serial port for communication. The -d -d -v options are used to print virtual port stream values to the console as well as the target. The EXEC option will run the executable (given by the COMMAND value) and connect to the virtual serial port using stdin & stdout. The port is created using the file id given by the link option. The first pty options creates the virtual serial port. It took me a while to find the correct combination of options to make this work. Here is the magic command you need: socat -d -d -v pty,rawer,link= EXEC:,pty,rawer RS-485 allows connection of up to 32 devices in a daisy chain fashion. So if you need to connect a bunch of things to 1 port, you should use an RS-485.How can you test and debug programs using serial port communication when you don’t have access to a physical serial port? Using the socat utility to create virtual serial ports which pipe port traffic to custom executables using stdin/stdout. RS-422 is generally used to connect to a single device also, but the type of information sent back and forth is simpler than that of the RS-232 protocol. Examples are an on/off switch for lights and a temperature sensor. Technically, RS-422 can transmit data up to 4,900 ft (1,500 meters), but most cables don’t run over 500 feet. RS-422 can connect devices at a much greater distance.
![serial port serial port](https://ae01.alicdn.com/kf/HTB1qJWDQFXXXXaBXFXXq6xXFXXXc/Nine-holes-serial-port-cable-cross-lines-to-DM-flash-the-COM-mother-mother-to-1.jpg)
RS-232 ports require 8 pins, whereas 422 and 485 only require 2 or 4 pins, so they are sometimes referred to as “2 pin COM ports.” Common applications are printers, scanners, and a mouse. It is the only standard that is implied. RS-232 can only connect a single device and at a distance of less than 50ft. These are its major limitations. If you have one device less than 50 ft away, you will use RS-232. RS-232 is the most commonly used, so much so that when someone says “serial port” they are expecting it to support RS-232. RS-232, RS-485 and RS-422 are protocols that specify how the electrical signals are sent out, coded and decoded to be understood by the computer. There are other protocols besides these three, but 232, 485 and 422 are by far the standard and most commonly used protocols on equipment.