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 line category: Serial, SerialOverUDP Device Redundant.
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
| Parameter | Meaning | Units | Default 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. | ms | 500 |
Wait First Timeout | The delay after sending the request and before reading the response. | ms | 200 |
Wait Timeout | The delay between the reply readings. | ms | 200 |
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/NO | YES |
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 hours | 24 |
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 days | 31 |
Full debug | Extra debug information about communication on the line including debug information about all gained I/O tag values. | YES/NO | NO |
I/O tag configuration
I/O tags for non-variable mode: Ai, Ci, TiA
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
| Address | Value type | Tech. units | Meaning |
|---|---|---|---|
| VER | Ci | - | Protocol version (0x01). |
| ECSID | Ci | - | The ID of conversion device, it is numbered from 0. |
| RTURDTM | TiA | - | RTU time of last reading the current data from the conversion devices. |
| ECSDTM | TiA | - | Time on the conversion device when the last reading the current data. |
| P | Ai | kPa | Current absolute pressure. |
| T | Ai | °C | Current temperature. |
| F | Ai | m3/hour | Instantaneous flow. |
| CLO | Ai | m3 | Current status of the counter for the calculated quantity of LO. |
| CHI | Ai | m3 | Current status of the counter for the calculated quantity of HI. |
| C | Ai | m3 | Current status of counter for calculated quantity, calculated as C = 10000 * CHI + CLO. |
| C8LO | Ai | m3 | Status of the counter for calculated quantity at 8:00 - LO. |
| C8HI | Ai | m3 | Status of the counter for calculated quantity at 8:00 - HI. |
| C8 | Ai | m3 | Status of counter for calculated quantity at 8:00, calculated as C8 = 10000 * C8HI + C8LO. |
| VH | Ai | m3 | Calculated quantity for the previous hour. |
| VD | Ai | m3 | Calculated 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
-
Document revisions
- Ver. 1.0 - 13. august 2010 - Creation of document
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