MODBUS SCT PPU 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


This protocol supports communication with the telemetric stations for remote measurement of gas by SCT company. It ensures the parallel measurement of data from the meters for wholesale and medium gas consumption of SPP-Distribúcia a.s.

Communication line configuration


Communication station configuration


  • Communication protocol "MODBUS SCT PPU".
  • The station address is a decimal number in the range of 0 to 255 (usually 1).


Station protocol parameters

Communication station - configuration dialog box - tab Protocol parameters.
These parameters influence some of the optional protocol parameters. You can define the following station parameters:

Table 1

ParameterMeaningUnitsDefault value
Retry Count
Maximum count of request retries. If no reply returns after a request had been sent, the station's status will change to a communication error.-2
Retry Timeout
Timeout before resending a request if no reply has been received.ms500
Wait First Timeout
The delay after sending the request and before reading the response.ms200
Wait Timeout
The delay between the reply readings.ms200
Max. Wait Retry
The maximum number of retries of the reply reading.-30
Send Valid Data Only
Send only valid data to the D2000 System. If it is set on YES, the Invalid values are not sent to the system.YES/NOYES
Future Data Filter
Filtering of data with a timestamp at least this value hours in the future. The setting to 0 hours disables this filter.0-168 hours24
History Data Filter
Filtering of data with a timestamp at least this value days in the past. The setting to 0 hours disables this filter.0-730 days31
Full debug
Extra debug information about communication on the line including debug information about all gained I/O tag values.YES/NONO

I/O tag configuration


I/O tags for non-variable mode: AiCiTiA


I/o tag address:

Table 2 contains the list of supported I/O tag addresses. The address is in the text format - the value from the column "Address".

Table 2

AddressValue typeTech. unitsMeaning
VERCi-Protocol version (0x01).
ECSIDCi-The ID of conversion device, it is numbered from 0.
RTURDTMTiA-RTU  time of last reading the current data from the conversion devices.
ECSDTMTiA-Time on the conversion device when the last reading the current data.
PAikPaCurrent absolute pressure.
TAi°CCurrent temperature.
FAim3/hourInstantaneous flow.
CLOAim3Current status of the counter for the calculated quantity of LO.
CHIAim3Current status of the counter for the calculated quantity of HI.
CAim3Current status of counter for calculated quantity, calculated as C = 10000 * CHI + CLO.
C8LOAim3Status of the counter for calculated quantity at 8:00 - LO.
C8HIAim3Status of the counter for calculated quantity at 8:00 - HI.
C8Aim3Status of counter for calculated quantity at 8:00, calculated as C8 = 10000 * C8HI + C8LO.
VHAim3Calculated quantity for the previous hour.
VDAim3Calculated quantity for the previous day.

All values of current data ("P", "T", "F", "CLO", "CHI" and "C") are sent with the time stamp according to "ECSDTM" (i.e. time on conversion device when the last reading the current data) to the D2000 System kernel. A period of data reading is set according to the conversion device. For a device with a mains power supply, it is about 10 minutes.

Time for RTU and conversion device is set remotely from dispatching of SPP-Distribúcia a.s.


Archival data loading

The values of "VH", "CLO", "CHI" and "C" can be read again from the so-called hour archive (max. 192 hour records).
The values of "VD", "C8LO", "C8HI" and "C8" can be read again from the so-called daily archive (max. 32 daily records).
Archival data can be loaded by the Tell command GETOLDVAL with the parameters a station name and time from which you need these data.

Literature


  • Parallel data transmission from the telemetry system of SPP-Distribúcia a.s. for wholesale gas customers, Revision 0.4, (c) SCT s.r.o. Košice, http://www.sct.sk.

Changes and modifications


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Document revisions


  • Ver. 1.0 - 13. august 2010 - Creation of document
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