Serial Output through a library?

  • zebra78

    zebra78 - 2006-03-01

    Is there a library that offers the ability to send a character string out through the host computer's serial port?


  • anverheul

    anverheul - 2006-03-16


    What about SysLibCom?

    It allows to open/close serial ports, and to read/write data from/to them.

    Or are you looking for something different?

    Arie N. Verheul

  • zebra78

    zebra78 - 2006-03-22

    I thought that was what I should use, but I can't seem to interpret the examples that I have found online. Can anyone post some working POU's with SysLibCom?


  • anverheul

    anverheul - 2006-03-23


    I've done quite some RS232 interfacing between CoDeSys controlled PLC and other equipment.

    Basically I've one task handling one serial port, with one 'low-level' POU (FB) handling basic RS232 actions (sending requests and receiving responses) and a 'higher-level' POU (PRG) determining which subsequent requests to send based on received responses.

    The higher level POU is continuously calling (polling) the low-level POU, checking it's status to determine if the low-level POU has finished transmitting the current request, or has finished reading the expected response etc.

    The low-level POU is a state machine with several (job)states and several (job)results, and it's only this POU that uses the functions from SysLibCom

    Some extra states are needed because the low-level POU is only sending a certain amount of bytes at a time, and also is reading a certain amount of bytes at a time, before handing over control to the higher-level POU (so that eventually also other tasks can get a chance to run).


    JOB_IDLE: ( Do nothing )

    JOB_SEND_REQUEST: ( Send request )

    JOB_SEND_REQUEST_CONTINUE: ( Send more bytes from (large)request );

    JOB_WAIT_FOR_ANSWER ( Wait for response )

    JOB_WAIT_FOR_ANSWER_CONTINUE ( Wait for more bytes from (large)response )

    JOB_PROCESS_ANSWER ( Process response )

    JOB_RETRY ( Send request again )









    Arie N. Verheul

  • zebra78

    zebra78 - 2006-03-23

    That sounds like a good idea, similar to what I would like to set up.

    I have tried using syslibcom.lib, but can't get even the SysComOpen function to work. My plc is configured with the target system being a PCI card with an integrated PLC installed inside my computer. This card does not have any serial ports, and I am hoping to use the host PC's RS 232 port, not a port on the target card.

    I have duplicated the code from this post on the German board: ... hlight=232

    but it cannot successfully open COM2.

    Is this possible?

  • deluxe79

    deluxe79 - 2008-10-06

    anverheul : Is it possible to have a copy of the source?

    Best regards,


  • mravlincek

    mravlincek - 2016-09-27

    bump: any updates to this?

  • shooter

    shooter - 2016-09-30

    check the codesys site


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