MICROTEL 700 communication protocol

Supported device types and versions
Communication line configuration
Communication station configuration
Alternative communication path
I/O tag configuration
Redundant system
Errors and problems
Detail implementation of protocol
Literature
Changes and modifications
Document revisions

Supported device types and versions

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Communication line configuration

• Category of communication line: Serial, SerialOverUDP Device Redundant, TCP/IP-UDP
• Parameters of serial line according to the setting of telemetry system.

Global parameters:

Communication station configuration

• Communication protocol: Microtel 700.
• Station address is a number within the range 1 to 253. Do not use the addresses 0, 254 and 255. They are filtered because they often occur at the beginning of response (error in transmission system).

Parameters of station protocol

Dialog window of station configuration - tab "Protocol parameters".

Table 1

Alternative communication path

With help of protocol parameters you can configure so-called alternative communication path for the particular station (only for SerialOverUDP Device Redundant and TCP/IP-UDP lines). If the communication via standard path elapses, the throughput of communication via the alternative path (when configured) is tested. The communication via the alternative path runs through TCP UDP form that is identical with that in SerialOverUDP Device Redundant line. The usage of alternative path is signalized by FLB flag and combination of FLN, FLO, FLP flags in the station.

I/O tag configuration

Possible I/O tag: Ai, Ao, Ci, Co, Di, Do, Qi.

The I/O tags of Ci and Co type are not used for a usual operation but only for a servicing. They display and record the values of modules in a raw form without the conversion to a physical value. The values of modules are 16-bit, thus a numerical in the range of 0 to 65535.

The structure of I/O tag address:

• All types of values require the setting of the basic address, so-called module, which is the number in the range of 0 to 63.
• Set the bit number in the range of 0 to 15 for Di, Do and 0 to 14 for Qi.
• For Ai and Ao - insert data for conversion of a raw form to the physical value, so-called "RTU table index", and minimum/maximum of physical value. RTU table index defines the range of raw values which is used in next recalculation (see Table 2). 

Table 2

The conversion of Ai inputs from the raw values "Raw_Value" to the physical value (Fyzikal_VALUE) is done according to this formula:

Scale = (Fyzikal_MAX - Fyzikal_MIN) / (RTU_MAX - RTU_MIN)

Offset = ((Fyzikal_MIN * RTU_MAX) - (Fyzikal_MAX * RTU_MIN)) / (RTU_MAX - RTU_MIN)

Fyzikal_VALUE = (Raw_Value * Scale) + Offset

The conversion of Ao outputs from the physical value to the raw one is done by the inverse function:

Raw_Value = (Fyzikal_VALUE - Offset) / Scale

The calculation of value "Scale" is modified to 0 (zero) so the recorded value is 0. This situation occurs if a user configures the physical minimum same as the maximum.

I/O tags of Qi type may use a special setting for the conversion of 2-bit input value to the required status one. The implicit conversion is stated in Table 3.

Table 3

Redundant system

This protocol supports two modes of activity:

1. The connection to "hot" server (HS). The protocol executes the active communication by sending the request for data according to configuration. 
2. The connection to "stand-by" server (SBS). The protocol just reads and analyzes the received data. To get the line and all the station to this status at any time, you can use the protocol parameter SCAN in the configuration of at least one station.

The change from SBS -> SS is done with a transient phase. It means that data are read during one minute to detect an inactivity on the communication line and whether the previous D2000 KOM, connected to HS server, has changed to mode 2.

Errors and problems

The error messages, mentioned below, may occur during the start or communication. It is recommended to activate the monitoring of communication in the configuration of line for easier identification of problem. You can choose it from these levels:

• Monitor (at least)
• Monitor & Disk (recommended)
• Disk (recommended)

When you set "Monitor & Disk" or "Disk", the file "line_name.LOG" occurs in the subdirectory "\TRACE" in application directory on the computer with the running communication process. This file contains all the debug and error messages.

Errors in the passive phase of communication

D2000 KOM connected to SBS server could display the following error messages:

Detail implementation of protocol

Supported and used functions: 

COMMAND 3 - Change of State Scanning

Scanning of the changes in the block of modules since the last data reading. This function is not used after starting the communication (all the values are unknown) and for the reading which comes after the communication error. In these situations, the value of all configured I/O tags is read.

COMMAND 2 - Data Streaming

The value reading of the modules. It optimizes the reading of the configured (configured only!) adjacent modules en bloc until completing of MODULE_CNT by one datagram.

COMMAND 7 - High Security Relay

The writing of the new value for binary I/O tag of Do type. It is executed in two phases.

COMMAND 4 - General Purpose Output

The writing of the new value for I/O tags of Co or Ao type.

Literature

• MICROTEL 700 Telemetry.

Changes and modifications

• January 9, 2008 - Alternative communication path.
• September 19, 2017 - Multiple hosts can be entered in alternative communication path, TCI/IP-UDP line is supported.

Document revisions

• Ver. 1.0 - September 2, 2003 - Document created
• Ver. 1.1 - January 9, 2008 - Document updated
• Ver. 1.2 - September 19, 2017 - Document updated