E+E Elektronik EE741 Series, Руководство пользователя

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User Manual EE741 Inline Flow Sensor for Compressed Air and Gases
5.2 Digital Interface
5.2.1 M-Bus (Meter Bus)
The M-Bus (Meter Bus) is a field bus for recording consumption data. Transmission runs serially
on a reverse polarity protected two-wire line. The EE741 flow sensor as M-Bus slave requires
a separate supply voltage. There is no prescribed specific topology (line or star) for the wiring.
Normal phone cable of type J-Y(St)Y Nx2x0.8 mm can be used. The max. cable length per
segment (primary addressed) is 250 m (820 ft).
The table below shows the structure of the consumption data sent by the sensing unit:
Header
68 Start of the telegram
4F 4F L-field (length)
68 Second starting signal
08 C-field (RSP_UD)
XX A-field (address)
Start user data
72 CI-field (variable data structure)
XX XX XX XX Identification number
A5 16 Manufacturer (0x16A5 … EUE)
01 Version
09 Medium (9 … compressed air)
XX Access number (consecutive)
00 Status
00 00 Signature
Data record 1: Volume flow
05 DIF (32 bit real)
3E VIF (volume flow in m³/h)
XX XX XX XX Cur. measured value
Data record 2: Temperature
05 DIF (32 bit real)
5B VIF (temperature in °C)
XX XX XX XX Cur. measured value
Data record 3: Mass flow
05 DIF (32 bit real)
53 VIF (mass flow in kg/h)
XX XX XX XX Cur. measured value
Data record 4: Consumption meter status
05 DIF (32 bit real)
16 VIF (volumes in m³)
XX XX XX XX Cur. consumption value
Data record 5: Flow velocity
05 DIF (32 bit real)
7F VIF (manufacturer-specific in m/s)
XX XX XX XX Cur. measured value
Data record 6: Volume flow
04 DIF (32 bit integer)
3B VIF (volume flow in 10-³ m³/h)
XX XX XX XX Cur. measured value
Data record 7: Temperature
04 DIF (32 bit integer)
59 VIF (temperature in 10-² °C)
XX XX XX XX Cur. measured value
Data record 8: Mass flow
04 DIF (32 bit integer)
51 VIF (mass flow in 10-² kg/h)
XX XX XX XX Cur. measured value
Data record 9: Consumption meter status
07 DIF (64 bit integer)
13 VIF (volumes in 10-³ m³)
XX XX XX XX
XX XX XX XX
Cur. consumption value
Data record 10: Flow velocity
04 DIF (32 bit integer)
7F VIF (manufacturer-specific in 10-²
m/s)
XX XX XX XX Cur. measured value
End user data
XX Checksum
16 End of telegram
Secondary addressing:
In addition to primary addressing, the EE741 flow sensor provides the option of secondary
addressing. The secondary address uses the fields of identification number, manufacturer,
version and medium. The M-Bus Standard https://m-bus.com/assets/downloads/MBDOC48.PDF
describes the exact sequence of the secondary addressing.
M-Bus setup:
Factory settings Adjustable values
Baud rate 2400 600, 1200, 2400, 4800, 9600
Data bits 8 8
Parity EVEN None, odd, even
Stop bits 1 1 or 2
Slave address 240 0...254
For several devices on the bus the max. recommended baud rate is 9600.