Update Interval:*
B873- 4 Channels 400 ms
B875- 8 Channels 710 ms
Out of Range 220 ms per channel
All registers are updated every 400 or 710 ms, as long as the inputs on all of the channels are within the valid range. 220 ms is added to the update interval for each channel either under or over range. The input is considered under range when the voltage is at -3 V or below. This keeps unused channels from adding time to the update interval.
NOTE: The over range indicator will be on or flickering, if the input on any channel is between .999 and -2.999 V or below 4 mA; but the 220 ms time will not be added to the update interval.
On an eight channel module, 2 channels are under range. All the registers assigned to the module will be updated every 1150 ms, until the inputs on the out of range channels return to the valid range. When they do, the update interval will return to 710 ms.
Update Interval =
(400 or 710) + (out of range channels X 220)
Using the example above:
(710) + (2 X 220) = 1150 ms
If one channel returned to the valid range, the update interval would reduce to 930 ms.
NOTE: As long as the channel is out of range, the register assigned to it will either have data of 0000 (4095 elevated), under range, or 4096 (8192 elevated), over range. (Refer to the data value reference chart)
* The update interval is the amount of time necessary to update the data for all the registers assigned to the module.
