Server protocols - general implementation rules

Introduction
Operation rules of servers protocols
Changes and modifications
Document revisions

Introduction

Since the version V7.0, D2000 system also supports some protocols, in which the process D2000 KOM implements the server (slave) side. It is concerning the following protocols:

This document describes the general rules which are valid for output I/O tags (output tags for D2000 system, input ones for client). There are also "mixed" client-server protocols (IEC 870-5-104 Server ,IEC 870-5-104, IEC 870-5-104 Sinaut), which have two types of output I/O tags:

  • 'client' output I/O tags - the same as for the other protocols,
  • 'server' output I/O tags - their specifications are described in the document.

Operation rules of server protocols

  • The values of 'server' output I/O tags are written also while the communication line / station fails, does not communicate or is down. They are to be send to the client after reconnecting the client.
  • When communication is interrupted, the values of 'server' output I/O tags are not invalidated.
  • Writing a 'server' output I/O tag is as follows:
    • During write, the output I/O tag does not pass through the status Transient. From this point of view, it is the same as setting the parameter Output mode in the tab Output control to the value Command in the I/O tag configuration.
    • If the communication with client is interrupted at the time of write, the write is marked as unsuccessful (it can be detected e.g. in ESL script using the actions ON ERROR, WAIT) but its value is valid, currently adjusted (in order to give new and valid value to the client after establishing the communication)
    • If the communication with client is OK at the time of write, the write is marked as successful
  • Configuration of the parameter Output mode for output I/O tag for 'server' and 'mixed' protocols is as follows:
    • If the the parameter Output mode is set to Value, the particular 'server' output I/O tag will not pass through the status Transient (see the previous point). The only difference between Value and Command is shown in control windows in the process D2000 HI. Command allows to repeat writing any value consecutively (e.g. for output I/O tag of Dout type, there are enabled the buttons ON and OFF at the same time - for value outputs, there is enabled just the opposite button to the current one).
    • For 'client' output I/O tags in the protocols of the series IEC104, transition through the status Transient depends on the ASDU type, which is set in the configuration of corresponding output I/O tag. ASDUs of the value type (1-40) are not being confirmed and therefore they do not pass through the status Transient. ASDUs of command type (45-64) are being confirmed and therefore these output I/O tags pass through the status Transient (confirmation/not conformation of value/command I/O tags is defined by contrast to D2000 system).
      For 'client' output I/O tags in 'mixed' protocols, which will be implemented in the future, the behavior will depends on the particular protocol.

Changes and modifications

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Document revisions

  • Ver. 1.0 – December 15th 2004

Related pages:

Communication protocols

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