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 the communication with the telemetric stations for remote measurement on gas meters of SCT company. It ensures the parallel measurement of data from the meters for wholesale gas consumption and medium one of SPP-Distribúcia a.s. .
Communication line configuration
- Communication line category: Serial, SerialOverUDP Device Redundant.
Communication station configuration
- Communication protocol "MODBUS SCT PPU".
- 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 optional protocol parameters. You can
define the following station parameters:
Table 1
| Parameter | Meaning | Units | Default value |
|---|---|---|---|
| Retry Count | Maximum retries of call. If any response is not received after these callings, the station switches to the communication error state. | - | 2 |
| Retry Timeout | Timeout before the retrying the call if any response has not been received. | ms | 500 |
| Wait First Timeout | Timeout between sending the call and first reading the response. | ms | 200 |
| Wait Timeout | Timeout between the response readings. | ms | 200 |
| Max. Wait Retry | Maximum retries of reading the response. | - | 30 |
| Send Valid Data Only | Send only valid data to D2000 System kernel. If it is set on YES, the Invalid values are not send to the system. | YES/NO | YES |
| Future Data Filter | Filtering data that has a time stamp shifted forward by this value from the current time (in hours). The setting on 0 hours switches off this filter. | 0-168 hours | 24 |
| History Data Filter | Filtering data that have the time stamp shifted back by this parameter from the current time (in days). The setting on 0 days switches off 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 | - | 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 counter for calculated quantity of LO. |
| CHI | Ai | m3 | Current status of counter for 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 counter for calculated quantity at 8:00 - LO. |
| C8HI | Ai | m3 | Status of 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 mains power supply, it is about 10 minutes.
Time for RTU and conversion device is set remotely from a 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 Tell command
GETOLDVAL with the
parameters a station name and time from which you need these data.
Literature
- Parallel data transmission from 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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