Siemens Milltronics BW500 Operating Instructions Manual page 107

External Totalizer Calculation Example:
Design Rate = 50 t/h (P011)
External Totalizer Resolution Selected = 0.001 (P638 = 1)
External Totalizer Contact Closure Time selected = 30 msec (P643 = 30)
External Totalizer Cycle Time = 60 msec (External Totalizer Contact Closure Time X 2)
1. Calculate the maximum number of pulses per second for the Contact Closure Time selected
(P643).
Maximum Number of pulses per second
= 1 / External Totalizer Cycle Time
= 1 / 0.060
= 16.6 (which is rounded to a whole number of 16 in the BW500)
2. Calculate the pulses per second required for the External Totalizer Resolution selected
(P638).
Pulses per second = ((Design Rate) * 150%) / (External Totalizer Resolution X 3600)
= (50 t/h X 150%) / ( 0.001 X 3600)
= 20.83
Because the required 20.83 pulses per second is greater than the maximum 16 pulses per
second, the External Totalizer Resolution of 0.001 will not allow the External Totalizer to track up
to 150% of the design rate. The External Totalizer Resolution will have to be increased to 0.01 or
the External Totalizer Contact Closure Time will have to be decreased.
The totalizers are reset through the master reset (P999), the totalizer reset (P648), or through
the keypad.
● master reset: the reset of all totalizer functions is included in the master reset.
● totalizer reset: totalizer reset can be used to reset internal totalizers 1 and 2, or totalizer 2
independently. Resetting the internal totalizers 1 and 2 resets the internal registers for
external totalizers 1 and 2.
● Keypad: pressing the following keys while in the RUN mode resets internal totalizer 1:
Placing the internal totalizers on to the display scroll of the RUN mode is controlled by the
totalizer display parameter (P647); displaying either one or both totalizers.
BW500 and BW500/L
Operating Instructions, 12/2016, A5E33482052-AD
Operation
8.10 Totalization
105