Level Averages (Tank parameter)
The level averages programmable parameter determines how many times to poll (and then average) level data from
the specified tank gauge. The specified number of level averages (polls) is completed before advancing to the next
gauge in the multiplex assignment. The level average factor directly affects the overall polling rate by the specific
gauge time delay times the level average factor (gauge poll rate = level time delay x level averages).
Number of Floats (Tank parameter)
The number of floats programmable parameter determines which level command (one or two float level command)
is sent to the DDA tank gauge. Two float commands take approximately 50% longer than single float commands for
the DDA tank gauge to acquire and transmit the level data. Consequently, the overall system polling rates will be
slower. The typical per gauge time delays are based on equations from the DDA gauge operation and installation
manual. Note that the level data time delays for Dx model DDA tank gauges are less than for LD models. Delay
times for two float DDA tank gauges are listed below in seconds. See previous section on level resolution for delay
times of single float DDA tank gauges.
‘Dx’ ‘LD’
tank gauge tank gauge
models models
Low resolution (0.1 inches) = 0.40 0.58
Medium resolution (0.01 inches) = 0.65 1.02
High resolution (0.001 inches) = 1.94 3.26
The actual time delays for level data may be slightly less than the values listed above since the level time delay is
also a function of tank gauge length. The shorter the gauge length, the slightly less the time delay will be. The above
listed values are based on the worst case time delays assuming maximum gauge lengths per model type (Dx and
LD).
Based on the user programmable parameters the overall polling rate can be approximated by the following equa-
tions.
Overall system delay time to scan all tank gauges for level and temperature.
1. (T1L)x(A1)x(NT)x(5) + (T1T) + (T2L)x(A2)x(NT)x(5) + (T2T) + ...... + (TnL)x(An)x(NT)x(5) + (TnT)
Where:
T1L = Tank gauge #1 level delay time (based on selected level resolution and # of floats)
T2L = Tank gauge #2 level delay time (based on selected level resolution and # of floats)
TnL = Tank gauge #n level delay time (based on selected level resolution and # of floats)
A1 = Number of level averages for tank gauge #1
A2 = Number of level averages for tank gauge #2
An = Number of level averages for tank gauge #n
NT = Number of tank gauges with temperature function enabled
T1T = Tank gauge #1 temperature delay time (based on selected temperature resolution)
T2T = Tank gauge #2 temperature delay time (based on selected temperature resolution)
TnT = Tank gauge #n temperature delay time (based on selected temperature resolution)
NOTE
Temperature delay time = 0 if temperature polling is
disabled for selected tank gauge.
92
To Next Page
Loading...
Need help?
General