Xylem Expert 7060_7070_Modbus - Manual (Page 19)

Communication protocol Serie30
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5.9 Function 73 : Read value of a channel (floating point)
Request:
DevAddr 73 CH CRC16_H CRC16_L
Response:
DevAddr 73 B3 B2 B1 B0 STAT CRC16_H CRC16_L
Exception errors:
2 If CH > 5
3 If message length is incorrect
32 If device is not yet initialised
Note:
A device can measure up to five signals (channels):
Two independent pressure sensors, P1 and P2. Plus the temperatures of pressure sensors TOB1 and TOB2 respectively. The
temperatures of the pressure sensors (TOB1, TOB2) are required for temperature compensation of the pressure signal. A
temperature sensor ( T ) can also be measured.
Please use function 32 to get the information which Channels are active.
CH0 is a calculated channel whose mode of functioning is defined in function 100.
On a standard pressure transmitter, only channels P1 and TOB1 are available. You can read out which channels are active via
function 100.
The measured value is returned in IEEE754 format (4-byte B0 ... B3).
CH Name Description Unit
0 CH0 Calculated channel (see function 32,33,100) *
1 P1 Pressure from pressure sensor 1 bar
2 P2 Pressure from pressure sensor 2 bar
3 T Additional temperature sensor °C
4 TOB1 Temperature of pressure sensor 1 °C
5 TOB2 Temperature of pressure sensor 2 °C
* Dependent on definition in function 32 or 100.
The STAT byte contains the current status.
Bit position .7 .6 .5 .4 .3 .2 .1 .0
Name /STD ERR2 TOB2 TOB1 T P2 P1 CH0
A set /STD bit indicates whether the transmitter is in Power-up mode, otherwise it is in Standard mode.
A set ERR2 bit denotes that a computation error has occurred in the calculation process for the analogue output. This occurs if
the analogue Signal is in saturation (depends on the scaling)
A set CH0, P1, P2, T, TOB1, TOB2 bit indicates that a measuring or computation error has occurred in the channel concerned.
For details in error-handling see chapter Error handling and recognition!