Datasheet ESRF-ESF

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When performing transaction with the ESRF-ESF sensors the returned data is always MSB

first. Flow is represented as a 16-bit, two’s complement number. The lowest number in the

Flow Data Register is 0x8000 (-32768 in Decimal) and the highest number is 0x7FFF (32767 in

Decimal). In unidirectional ESF sensors output data higher than 0x7FFF must be ignored.

Calibrated flow (in SLPM) can be calculated using the following formula:

An example of unidirectional flow:

Flow Register Byte [0] = 0x3F

Flow Register Byte [1] = 0xFF

Using the formula (Eq 1) and assuming a full scale flow of 200 ln/min, the calculated output

should be 109.9932 ln/min

Eq. 1

An example of bidirectional flow:

Flow Register Byte [0] = 0xFC

Flow Register Byte [1] = 0x18

Using the formula (Eq.1) and assuming a full scale flow of 200 ln/min, the calculated output

should be –6.7139 ln/min

7. Data & Register Description

The ESRF-ESF sensors provide measurement and status data. The measurement data are

flow rate and temperature whilst the status data refer to the sensors factory programed

serial number. The data are stored in specific data registers as described below. The readout

is performed by using multibyte read transactions.

ADDRESS

REGISTER NAME

TYPE

DEFAULT VALUE

(Hex)

MNEMONIC

0x00

Calibrated Flow Byte 1

R

Variable

CAL_DATA[15:8]

Calibrated Flow Byte 2

R

Variable

CAL_DATA[7:0]

Flow Data Register [0x00]