Conference noted::lat

    Hi Denny,
    
        I still am not sure what you want to do (are you wanting to upgrade
    versions of VMS via the terminal server ???).
    	
       > 1.  Does the Dedicated node in the port definition limit ONLY that
       >     node to access the port?
    The port dedicated service specification limits the user whose
    terminal is connected to that port to nodes offering the specified
    service. 
    
    
       > 2.  What is the significance of the Dedicated service?  Where
       >     is/should that service be defined?  How is it used?
    
    The DEDicated service usually specifies a node on the network that you
    want the terminal user to login on. It can also point to a LAT service
    offered by a terminal server as is the case for a dial out modem pool.
    
    
       > 3.  Does the OpenVMS LATCP require any "special" CREATE and/or SET
       >     PORT characteristics to allow the application to successfully
       >     connect to and communicate with the instrumentation connected to 
       >     the DECserver?
    
    I don't understand where you are going with this. If you have
    a dedicated service on a terminal server port, why do you want to
    create an LTA device in LATCP mapped to the same port. Where will the
    connection be initiated, from the terminal server port or the vms
    system ? Depending on what you are trying to do, there may be "special"
    create / set port characteristics you may want to consider. 
    
    
    Gene 

    Gene,
    
    >    I still am not sure what you want to do (are you wanting to upgrade
    >versions of VMS via the terminal server ???).
    	
    I'm trying to convert a customer's operating environment from using
    local terminal controllers to terminal servers (i.e. TXA to LTA
    devices).  The is currently using VAX 4000-200's w/ CXY16 controllers
    (TXAs), and has run out of gas; is looking to replace the VAX 4000-200s
    with VAXstation 4000-90s and terminal servers (since I can't connect
    the CXY16's to a 4000-90).  
    
    These sytems run a large application consisting of many proceses, which
    collect data and drive special displays through these terminal ports. 
    As the application starts up, it opens channels to the ports and begins
    communication with instrumentation and devices connected to them!
    
    There will be VMS upgrades involved in this project, but that will have
    minimal bearing on this discussion, only to provide the operating
    environment I'm working in - currently VMS 5.5-2.
    
    >   > 1.  Does the Dedicated node in the port definition limit ONLY that
    >   >     node to access the port?
    >The port dedicated service specification limits the user whose
    >terminal is connected to that port to nodes offering the specified
    >service. 
    
    So if I under stand this, and I have a Terminal port configured with
    
       SET PORT 1 DEDICATED SERVICE MMI NODE HLAKE
    
    (node HLAKE is a VAX/VMS system in this case), that VMS system must
    offer the service MMI for a successful connection initiated from that
    VMS system.  Or in otherwords, only a node whose name is HLAKE AND is
    offering a service named MMI will be allowed to connect to this port. 
    Is this right?
    
    (oh, by the way the terminal server ports are also configured with
    DYNAMIC ACCESS).
    
    
    >   > 3.  Does the OpenVMS LATCP require any "special" CREATE and/or SET
    >   >     PORT characteristics to allow the application to successfully
    >   >     connect to and communicate with the instrumentation connected to 
    >   >     the DECserver?
    
    >I don't understand where you are going with this. If you have
    >a dedicated service on a terminal server port, why do you want to
    >create an LTA device in LATCP mapped to the same port. Where will the
    >connection be initiated, from the terminal server port or the vms
    >system ? Depending on what you are trying to do, there may be "special"
    >create / set port characteristics you may want to consider. 
    
    As I stated in my base note, I'm trying to reverse engineer a
    customer's environment.  The application I mentioned above seems to
    have support for either TXA or LTA connections.  I found a TSM script
    which is used to set a terminal server environment. I don't yet know
    WHY the terminal server ports are configured with a dedicated node and
    service.  I'm just trying to figure out what it all means, and get the
    applications to successfully connect/communicate with the
    instrumentation through LAT devices.  I'm more than willing to
    eliminate the dedicated node/service from the port definitions, but NOT
    before I understand any/all implications!
    
    The connections will be initiated from a VAX/VMS process. I need to
    create LTA devices for that application/process to connect to!

    Denny,
    
    if the application can support LTA devices, you should just set the
    DECserver ports to ACCESS = REMOTE and create/set LTAx ports on the
    OpenVMS VAX system to point to the DECservers and ports, where the 
    instrumentation devices are connected.
    
    Communication with those devices is only possible AFTER the LAT
    connection has been established. Any data from those devices sent
    BEFORE a LAT session has been established will be lost...
    
    Setting a DECserver port to DEDICATED SERVICE xxx NODE yyy should only
    allow a connection to node xxx for service yyy, even if other nodes
    would offer service yyy as well.
    
    Volker.

    After some serious "playing around" yesterday, I have come to the
    conclusion that a DEDICATED SERVICE xxx NODE yyy affects ONLY locally
    initiated connections, and not remotely initiated connections (reverse
    LAT).  Is this right?
    
    Some of my applications are NOT successfully connecting to the LTA
    devices, and I was thinking that LAT on the VMS side was NOT configured
    properly to handle the DEDICATED service port attribute; but now I'm
    thinking otherwise.  I think I'm missing some subtle application
    configuration issue, and am pursuing that from this point on!
    
        Thanks for everyone's help,
          Denny

    Denny,
    
    if the application does not use LAT CONNECT QIOs, then it MUST do a WRITE
    as the first thing on the LTA device. This would transparently create the
    'host initiated' LAT session.
    
    Did you read the IO reference manual regarding LAT (or see MC LATCP
    HELP CREATE PORT/DEDIC and HELP SET PROT/SERVICE) for maybe another
    method of creating LAT session sfrom the DECserver to the VAX... I've
    never used that, but that method might explain the settings on your
    terminal server port.
    
    Volker.