Select Channel Enable (Bit 11); Unused Bits (Bits 12-15); Channel Data Word - Allen-Bradley SLC 500 User Manual

5-12 Channel Configuration, Data, and Status

Channel Data Word

Module Input Image (Data Word)
I:e.0
15
I:e.1
15
I:e.2
15
I:e.3
15
Publication 1746-UM007C-EN-P - July 2004

Select Channel Enable (Bit 11)

You use the channel enable bit to enable a channel. The
thermocouple module only scans those channels that are enabled. To
optimize module operation and minimize throughput times, unused
channels should be disabled 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 on page 5-13.)
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
thermocouple module sets the channel status bit (bit 11) in the
channel status word.

Unused Bits (Bits 12-15)

Bits 12-15 are not defined. Ensure these bits are always cleared (0).
The actual thermocouple or millivolt input data values reside in I:e.0
through I:e.3 of the thermocouple module input image file. The values
present will depend on the input type and data formats you have
selected. When an input channel is disabled, its data word is reset (0).
14 13 12 11 10
14 13 12 11 10
14 13 12 11 10
14 13 12 11 10
CH 0 Channel Data Word
9 8 7 6 5
CH 1 Channel Data Word
9 8 7 6 5
CH 2 Channel Data Word
9 8 7 6 5
CH 3 Channel Data Word
9 8 7 6 5
4 3 2 1 0
4 3 2 1 0
4 3 2 1 0
4 3 2 1 0