IOtech MultiScan 1200, User Manual

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214 Chapter 13: System Operation TempScan / MultiScan User's Manual
Comparing Buffered Data to HLL Data
With the TempScan/1100 unit, unless scans are being collected at the maximum possible frequency, the
HLL Registers may detect alarm states that will not appear in the collected data. Since the HLL
Registers are being updated at the maximum possible frequency, which may be considerably faster than
the scan frequency as set by the programmed scan interval, an alarm state may be detected even though
no such value can be found in the buffered scan data. If such a situation is not preferred, decreasing the
programmed scan interval (thus increasing the scan frequency) will decrease the possibility of such an
event. At the maximum possible scan frequency, this situation is guaranteed not to occur.
With the MultiScan/1200 unit, the HLL Registers are being updated at the same frequency as set by the
programmed scan interval. Hence, all detected alarm states will appear in the collected data.
Status-Reporting & Mask Registers
The TempScan/1100 or MultiScan/1200 has several internal 8-bit registers dedicated to status and
event reporting, where each bit represents a certain condition, event or error. You can access these
registers via commands issued from the PC/IEEE 488 controller.
Status-Reporting & Mask Registers