FLOWSIC600 · Operating Instructions · 8010458 V 2.0 · © SICK MAIHAK GmbH 17
Product Description
2.2.2
Meter States
2.2.2.1 Status: Measurement valid
The “Measurement” status is the standard Meter state of the FLOWSIC600. Frequency
outputs and current output are updated cyclically and indicate the actual volume and
volumetric flow rate. In addition, the analog signal can indicate the actual flowrate,
corrected volumetric flowrate, SOS (speed of sound) or VOG (velocity of gas) The digital
output “Direction of flow” is updated in accordance with the direction of the volumetric
flow. The digital output “Valid measurement” (active) represents the status of the
measurement. Positive (forward) and negative (reverse) volumetric flow rates are
integrated and saved in separate internal memory sections.
The MODBUS interface allows the query of all parameters and signals at any time without
interfering with the function of the system.
Each measurement initiated by the system controller includes one full transit time
measurement with, and one against the direction of flow on each path. The result of each
measurement is written to a mean value memory to be used in further calculations. The
size of this memory block and thus the device response delay can be modified through the
parameter in register #3502 “AvgBlockSize”. If no result can be calculated due to poor
signal quality, this measurement is registered as an invalid attempt in the mean value
memory. The mean value is formed in a variable averaging process including all valid
measured values in the memory.
If the number of invalid measurements on a path exceeds a predefined limit (register
#3514 “Limit%Error”), the measuring system activates the “Check request” status.
2.2.2.2 Status: Check request
This status becomes active if one measuring path has failed and the adaptive path failure
compensation has been activated. The multi-path FLOWSIC600 system is able to
compensate for this failure. Measurement is continued with reduced accuracy. If a path
fails while the path failure compensation is deactivated, the measuring system will activate
the “Measurement invalid” status.
Moreover the check request status becomes active when the system alarms 2002 (“No
HART communication to temperature transmitter”), 2003 (“No HART communication to
pressure transmitter”), or 2004 (“Maximum pulse output frequency exceeded”) become
active (see table
→
pg.86, 7.2.1).
2.2.2.3 Status: Measurement invalid
If the quality of received signals is deficient in more than one measuring path, the SPU
must mark the measured value invalid and activate the meter status “Measurement
invalid”. However, the SPU will cyclically try to re-establish valid measurements. As soon as
the signal quality and number of valid measurements meet the required criteria, the SPU
will automatically change back to the “Measurement valid” or “Check request” status.
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