Filter Frequency Selection (Bits 9 And 10); Channel Enable Selection (Bit 11) - Allen-Bradley SLC 500 1746-NR4 User Manual

Table 5.N
Bit Descriptions for Temperature Units Selection
Binary
Select
Value
0 degrees Celsius
1 degrees Fahrenheit

Filter Frequency Selection (Bits 9 and 10)

Table 5.O shows the descriptions for bits 9 and 10. The channel filter
frequency bit field lets you select one of four filters available for a channel.
The filter frequency affects the channel update time and noise rejection
characteristics (refer to chapter 4 for details).
Table 5.O
Bit Descriptions for Filter Frequency Selection
Binary
Select
Value
provide both 50 Hz and 60 Hz AC line noise filtering. This setting increases the
00 10 Hz
channel update time, but also increases the noise rejection.
01 50 Hz provide 50 Hz AC line noise filtering.
10 60 Hz provide 60 Hz AC line noise filtering.
provide 250 Hz AC noise filtering. This setting decreases the noise rejection,
11 250 Hz
but also decreases the channel update time.

Channel Enable Selection (Bit 11)

Table 5.P shows the description for bit 11. You use the channel enable bit to
enable a channel. The RTD module only scans those channels that are
enabled. To optimize module operation and minimize throughput times, you
should disable unused channels by setting the channel enable bit to zero.
When set (1), the channel enable bit is used by the module to read the
configuration word information you have selected. While the enable bit is
set, modification of the configuration word may lengthen the module update
time for one cycle. If any change is made to the configuration word, the
change must be reflected in the status word before new data is valid. (Refer
to Channel Status Checking on page 5–19.)
While the channel enable bit is cleared (0), the channel data word and status
word values are cleared. After the channel enable bit is set, the channel data
word and status word remain cleared until the RTD module sets the channel
status bit (bit 11) in the channel status word.
Chapter 5
Channel Configuration, Data, and Status
If you want to
display the channel data word in degrees Celsius.
display the channel data word in degrees Fahrenheit.
Description
5–13