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System-10-LON Network Interface Installation Guide 07/13 - 0654-4 / 16751 Page A-3
INTEGER FORMAT OUTPUT NETWORK VARIABLES
Integer format output variables are limited to 2 bytes of data. For this reason, the maximum number that
can be transmitted in this format is 65,535. Values for both rate and total data from the Btu meter will often
exceed this limit. For this reason, energy rate data is scaled and energy totals are transmitted in segments
using multiple variables. This is explained in detail below.
Volume and Energy Rate Variables
The integer output network variables for volume and energy rate are described in the table below. Column
1 contains a brief description of the network variables. Column 2 contains the network variable names.
Column 3 contains the Lon SNVTs used for each variable. Column 4 contains the engineering units and
column 5, the valid range for each variable. Please note that while the oating point variable for energy
rate is transmitted in Watts, the integer network variable is transmitted in kW to ensure that the maximum
rate never exceeds the register capacity.
Integer Output Network Variables
Description Variable Name SNVT Name Engineering Units Valid Range
Flow (volume) rate nvoVolRateLi SNVT_ow Liters/Sec 0 to 65535
Mode status indicator nvoModeStatus SNVT_char_ascii
Supply temperature nvoSupplyTempi SNVT_temp_p ° C -17.778 to 260.0
Return temperature nvoReturnTempi SNVT_temp_p ° C -17.778 to 260.0
Delta temperature nvoDeltaTempi SNVT_temp_diff_p ° C -327.68 to 327.66
Energy rate nvoEnrRateKWi SNVT_power_kilo KWatts 0 to 65535
Volume and Energy Total Variables
The integer output network variables for volume and energy total are described in the table below. Column
1 contains a brief description of the network variables. Column 2 contains the network variable names.
Column 3 contains the Lon SNVTs used for each variable. Column 4 contains the engineering units and
column 5, the valid range for each variable.
Please note that while the oating point variable for volume total is transmitted in liters, the integer
network variable for volume total is transmitted in kLiters. This is done to increase the maximum total
that can be transmitted via the integer variable. Total(s) must be reset before the accumulated value
exceeds 6553.5 kliters using nviResetVol1a and/or nviResetVol2a. If this is not done, nvoVol1KLi and/or
nvoVol2KLi will over range and continue to indicate 6,553.5 kliters (1,731,252 gallons) until the
System-10’s internal total rolls over to zero.
A separate integer SNVT is also available to transmit ow totals in liters. This variable is only used in
special small pipe applications as the maximum total it can accumulate is only 65,535 liters (17,312
gallons) before it must be reset.
Energy totals are handled in a slightly different way. The oating point variable for energy total is
transmitted in Btu but the integer network variable for energy total is MBtu. This total will over range at
65,535 MBtu. The internal total stored in the Btu meter will not roll over until it exceeds 99,999.99 MBtu.
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