XENTRA 4900 communication protocol

Supported device types and versions 
Communication line configuration
Communication station configuration
I/O tag configuration
Literature
Changes and modifications
Document revisions

Supported device types and versions

Communication supports reading data from Servomex XENTRA 4900 devices.

Communication line configuration

Required communication line parameters:

• Communication line category: Serial.
• Baud rate of 2400,4800,9600 or 19200 Bd - according to the device settings.
• The number of stop bits - according to the device settings.
• The number of data bits - according to the device settings.
• Parity - according to the device settings.

For other parameters, see the topic Communication line - configuration dialog box.

Communication station configuration

• Communication protocol: Servomex XENTRA.
• The station address is not used (one XENTRA device is being connected on the line)

Station protocol parameters

The following station protocol parameters can be defined:

Table 1

A string containing the protocol parameters is being defined as follows:

Keyword=value;Keyword=value; ...

Example:

WT=2000;MWR=40;

If a keyword with an invalid value is used in the initialization string, a corresponding default value according to table 1 will be used.

I/O tag configuration

Possible I/O tag types: Ai (Analog Input) or TiA (Absolute Time Input).

Example of received data message:

14-07-97;16:15:32;06; O2 ; 20.95; % ; CO ; 6.2;vpm; NO ; 3.5;vpm; NOx ; 0.2;vpm;||||||; 0.0; mA;||||||; 0.0; mA;1EBF;

From the message format implies, that individual items are semi-colon separated (;) - it defines I/O tag addressing. In the tab Address of the I/O tag configuration dialog box, there is required one number - item index in the data packet. Index is defined as a decimal number from 1 (or as a hexadecimal number with a hash at the beginning, e.g. #0A). It means that the index of 1 contains the item 14-07-97, the index of 5 contains the item 20.95, the index of 8 contains the item 6.2, etc. 

Ai type: there can be used just the indexes (addresses) of I/O tags, which can be converted to a real number. In the example above: indexes (addresses) of 3,5,8,11,14,17 and 20 (their values are: 6.0, 20.95, 6.2, 3.5, 0.2, 0.0 and 0.0). If the item can't be converted to a real number, the I/O tag value is invalid.

TiA type: there can be configured only one I/O tag of TiA type - the index (address) of 0. The I/O tag gets the time and date from the items with indexes 1 and 2. In the example above - it is the value of 16:15:32 14-07-1997.

I/O tag value time

Times of new values of I/O tags can be:

• acquired from the data packet (identical with the value of the I/O tag of TIA 0)
• real-time of the computer, when the value was assigned to.

One of the options is being defined by means of the station protocol parameter XT (see table 1).

Literature

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Changes and modification

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Document revisions

• Ver. 1.2 – February 8th, 2000 – update of 4.07 and 4.10 versions
• Ver. 1.3 - April 12th, 2002 - the protocol parameters SC added