Rockwell Automation Current Input Module - Manual (Page 27)

4Ć9
As the number of input samples increases, the time span of
averaging increases, which results in a less current input value for
use in the application program. See figure 4.9 for an equation to
determine the amount of time needed to calculate an average input
value for registers 0 to 15.
# of
configured
channels
cycle
frequency
time
+
system
overhead *
# of
samples
= time the value
in registers 0Ć15
was averaged over
Where:
# of configured channels that have cycle averaging enabled = 1Ć16
cycle frequency time = 20 msec for 50 Hz
16.6 msec for 60 Hz
system overhead = 5 msec
# of samples = 1Ć60
averaged time = time in seconds
*
Figure 4.9 Ć Equation for Determining the Input Value Averaging Time
4.1.13 High High Alarm Register (Register 27)
Register 27 defines the High High alarm limit. If a channel's input
value exceeds this limit, the channel's corresponding bit in register 16
is set to one. The value in register 27 is a 15Ćbit signed integer. This
value must be in engineering units if scaling is used. If scaling is
used, this value must be equal to or smaller than the Maximum
Scaling Value (register 24) and larger than the Minimum Scaling
Value (register 25). Unscaled data can range from 0 to 4095.
If register 27 does not contain an alarm value greater than or equal to
the High alarm value, a configuration error will result in register 22. At
powerĆup, the register is set to a default value of 4094.
4.1.14 High Alarm Register (Register 28)
Register 28 defines the High alarm limit. If a channel's input value
exceeds this limit, the channel's corresponding bit in register 17 is set
to one. The value in register 28 is a 15Ćbit signed integer. This value
must be in engineering units if scaling is used. If scaling is used, this
value must be equal to or smaller than the Maximum Scaling Value
(register 24) and larger than the Minimum Scaling Value (register 25).
Unscaled data can range from 0 to 4095.
If register 28 does not contain an alarm value greater than the Low
alarm value, a configuration error will result in register 22. At
powerĆup, the register is set to a default value of 4085.