Message format

In the voltage message, a series of voltage values are sent and the oldest one is first.

<Message Id> # <header>,<voltage values>

  • Message Id. 18#

  • Header. Format Number, Meter type, Number of samples, Collection Interval, Scaling Factor

  • Voltage Values. First VA, First VB, First VC, Second VA, Second VB, Second VC, and so on

Format voltage values as integer = floor( Voltage *  10^Scaling factor )

Data size

Message Id: 18# = 3 bytes

Header:

Format Number : 1 byte

Meter type : 2 byte [Max Value possible = 45]

Number of samples : 6 byte [Max Value possible = 172800]

Collection Interval : 6 byte [Max Value possible = 172800]

Scaling Factor : 1 byte [Max Value possible = 5]

Max Header Size = 1 + 2 + 6 + 6 + 1 + 4(Commas) = 20 bytes

Remaining: Payload = 256 - 3 - 20 - 1(comma)  = 232 bytes 

Payload Capacity Assuming Max Header Size (232 bytes)

  • Assuming Scaling Factor as 5

  • One Voltage value will have max 8 byte (3 digits before decimal point, 5 digits after decimal point)

    • 25 samples (single phase. 8 byte + 1 byte(comma) per phase)

  • 8 samples (for all phases included. 24 bytes + 3 bytes (commas) for 3 phases)

  • Assuming Default Scaling Factor

    • One Voltage value will have max 5 byte (3 digits before decimal point, 2 digits after decimal point)

    • 38 samples (single phase. 5byte + 1byte(comma) per phase)

  • 12 samples (for all phases included. 15 bytes + 3 bytes (comma) for 3 phases)

  • Header Size with default values

  • Format Number: 1 byte

  • Meter type: 1 byte [Default Value = 2]

  • Number of samples: 1 byte [Default Computed Value = 3]

  • Collection Interval: 3 byte [Default Value = 300]

  • Scaling Factor: 1 byte [Default Value = 2]

  • Max Header Size = 1 + 1 + 1 + 3 + 1 + 4(Commas) = 11 bytes

  • Remaining: Payload = 256 - 3 - 11 - 1(comma)  = 241 bytes 

Payload Capacity Assuming default Header Size (241 bytes)

  • Assuming Default Scaling Factor

  • One Voltage value will have max 5 byte (3 digits before decimal point, 2 digits after decimal point)

    • 40 samples (2S meter gives Voltage on Phase A only. 5 byte + 1 byte(comma) per phase)

Example

For inputs:

  • Format Number. 0

  • MeterType. 12S Meter

  • Number of Samples. 4

  • Collection Interval. 900 sec

  • Scaling factor. 2

  • First voltage values. VA=240.13, VC=241.69 (As integer: 24013, 24169)

  • Subsequent Voltage values

    • 240.99, 241.23

    • 241.13, 241.65

    • 240.85, 240.94

Message:

  • Message Id. 18

  • Header. 0,12,4,900,2

  • Voltage Values. 24013,24169,24099,24123,24113,24165,24085,24094    

Sample output:

18#0,12,4,900,2,24013,24169,24099,24123,24113,24165,24085,24094