Section 6: Meter operation

Reference, Installation, and Operations Manual

June 2013

3-9000-743 Rev S

 

 

6.5.1Hardware configuration

The Daniel Mark III Ultrasonic Gas Flow Meter communicates serially with the Daniel GC using Option Board Port C in either RS-232 or RS-485 (half duplex) mode. Refer to “Port C Driver Configuration” in Section 3.5.1 for further information on connecting the two devices.

6.5.2Software configuration

It is recommended that the Daniel MeterLink Field Setup Wizard be used to configure the GC interface (see Section 5.6.13).

The GasPropertiesSrcSel data point is used to select whether the gas property data is live (read from a GC) or fixed. The GCSerialPort data point is used to either disable the GC interface or select (Option Board) Port C for communicating with the GC. These two points are automatically set via the Daniel MeterLink Field Setup Wizard.

The following information is required in order to configure the Daniel Mark III Ultrasonic Gas Flow Meter to interface with a GC:

•the GC Modbus communication configuration:

–protocol (GCProtocol)–baud rate (GCBaud)–Modbus address (GCModbusID)

•the desired stream number (GCStreamNumber) and the length of time to wait for the desired stream number (GCDesiredStreamTimeout), and

•heating value configuration:

–type of heating value (GCHeatingValueType)–unit (GCHeatingValueUnit)

The software configuration also allows for the selection of how the meter is to respond when the GC-read data is considered invalid (GasPropertiesSrcSelGCAlarm): whether to ‘freeze’ the ‘in-use’ gas property data to the last good GC-read data or to use fixed gas property data instead.

The length of time to wait for the desired stream (GCDesiredStreamTimeout) is not configurable within the Daniel MeterLink Field Setup Wizard. It is, however, configurable using the Daniel MeterLink Edit/Compare Configuration utility. Its default value is 100 minutes and limits are [6, 255 min]. The total number of streams and the update time per stream should be taken into account when updating this parameter.

6.5.3Gas property data

The gas property data read from the GC includes gas composition, heating value, and specific gravity (relative density).

The gas composition includes the 21 standard components plus C6+ and Neopentane (see

Table 6-8for a list of data point names). Refer to Section 6.1.16 for further information on how the GC-read gas properties are mapped to the ‘in-use’ gas property data points.

The GC-read heating value and specific gravity are stored in the HeatingValueGC and Specific- GravityGC data points, respectively.

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Hardware configuration