Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 37)

4–6 Preliminary Operating Considerations
Publication 1746Ć6.8 - April 1997
The table below gives you the turn-on, turn-off, and reconfiguration
times for enabling or disabling a channel.
Description Duration
➀
TurnĆOn Time
The time it takes to set the status bit (transition
from 0 to 1) in the status word, after setting the
enable bit in the configuration word.
101 to 107 msec
maximum
TurnĆOff Time
The time it takes to reset the status bit
(transition from 1 to 0) in the status word, after
resetting the enable bit in the configuration
word.
1 to 7 msec
maximum
Reconfiguration
Time
The time it takes to change a channel
configuration if the device type, filter frequency,
or configuration error bits are different from the
current setting. The enable bit remains in a
steady state of 1. Changing data format does
not require reconfiguration time.
101 to 107 msec
maximum
➀
The duration varies with the number of channels that are enabled.
By writing to the status file in your modular SLC processor you can
disable any chassis slot. Refer to your programming device’s manual
for the slot disable/enable procedure.
!
ATTENTION: Always understand the implications of
disabling a module before using the slot disable
feature.
Input Response
When a slot is disabled, the 1746-NI8 module continues to update its
input image table. However, the SLC processor does not read inputs
from a module that is disabled. Therefore, when the processor
disables the module slot, the module inputs appearing in the
processor image table remain in their last state, and the module’s
updated image table is not read. When the processor re-enables the
module slot, the current state of the module inputs are read by the
processor during the subsequent scan.
Output Response
The SLC processor may change the module output data
(configuration) as it appears in the processor output image.
However, this data is not transferred to the module. The outputs are
held in their last state. When the slot is re-enabled, the current data
in the processor image is transferred to the module.
Channel TurnĆOn, TurnĆOff,
and Reconfiguration Times
Response to Slot Disabling