Data Logging

An area of internal Flash memory is dedicated to recording selected meter readings. Up to 20 parameters in each time stamped record. The precise date and time used for the timestamps is acquired from an SNTP server using the internet. Each time stamped record contains up to 20 individual measurements read by the meter.

Records are regularly sent to an ftp server on the network where they can be accessed to provide comprehensive reports. If the ftp server is unreachable for any reason then any data not yet sent will be included in the next successful transmission. This ensures that a complete record is maintained on the ftp server. Two intervals can be independently configured using a standard web browser. The time between records held in the internal flash memory is set in the log interval. The interval between ftp transmissions is set as the ftp interval. A log interval of 900 seconds with an ftp interval of 3600 seconds would send one file every hour containing, on average, four data records.

Datalog.html is used to set the data logging parameters within the meter. http://meterURL/Datalog.html.

Network.html will have been used to configure the network parameters required for time stamping and for ftp transfers. If DNS server details are not known then the OpenDNS servers at IP addresses 208.67.222.222 and 208.67.220.220 may be used. The gateway address will commonly be the address of the router which provides access to the internet. If a Windows XP IE browser is being used then these details can be displayed by typing ipconfig /all in a command prompt window.

The meter uses passive ftp to send data files so will not normally require any changes to the firewall or router settings. The meter does not use dhcp but instead has a static IP address.

If the meter web server pages are to be viewed from the internet side of the firewall then access will have to be provided to port 80 or port 8080.

If complete data log files are to be copied from the meter then access will also be required to port 69.

Data structures

Each file name is made up of the meter MACi address, date and time separated by the underline character

ftp Transmitted data log structure
Time Stamp (20070716_235837 + parameter 1 value(2435) + parameter 2 value(5000) ……….+ parameter 20 value(5)

Example data file

001BE5101010_070717_074354
  070717_073046,2,919,81,2449,944,187,81,2452,100,3226,49,77,22,162,499,2,2,2,4,5
  070717_073546,2,923,81,2447,944,188,80,2445,100,3226,49,77,21,146,499,2,2,2,4,5
  070717_074046,2,927,81,2445,944,187,80,2443,100,3226,49,77,21,148,499,2,2,2,4,5
  

Values are transferred as raw 16 bit integers without any decimal points. The decimal point position or multiplier is available as a parameter or can be considered fixed as described in the meter Modbusi manual. Log files can simply be combined by using the DOS copy command, eg copy 001BE5* total.csv , and opened in Excel. If the _ character is included as a field separator the date and time can be in separate columns

Network link disruption

When the ftp link is disrupted the internal 1Mbit memory will continue to store records but, when full, will overwrite the oldest records with the most recent values. If the data log interval is 15minutes then records for some 31 days will be stored within the meter.

Meter internal Flash record format 352bits/20 parameter record

Time Stamp (32 bits) + parameter 1 value (16 bits) + parameter 2 value (16 bits) ………….+ parameter 20 value (16 bits)

Useful Modbus parameter registers (from the Cube Modbus manual).