ASF1400 datasheet(5/9 Pages) ETC2

5 / 9 page

ASF1400 Bidirectional Mass Flow Meter

2 Pins and Digital Interface

The measurement values are provided as a signed

floating point number together with the corresponding

unit (sccm for mass flow, C for temperature). In case

of an overflow, the output shows oF.

G N D

V D D

/ C S

M O S I

M I S O

S C K

R x D

T x D

2.3 Serial Peripheral Interface (SPI)

The in earlier versions available SPI interface is due

to changes in electronic components no longer

supported.

Figure 6: ASF1400 pin out.

3 Configuration and Commands

GND and VDD (Power Supply)

The ASF1400 device accepts a set of commands

through its RS-232 interface (see table 3 for valid

commands; for correct settings of the RS-232 refer to

Section 2.1).This allows the user to configure the

ASF1400 device. Since the configuration is stored in

the internal EEPROM, it is maintained after power

breaks.

The ASF1400 requires a voltage supply of between 7

V and 18 V. Since this voltage is internally regulated,

there are no stringent requirements as far as ripple

and stability are concerned.

2.1 Connector

With the exception of the stop s command, all

commands have to be terminated by the return key

(

↵, ASCII #10 or #13). After completion of a

command, the ASF1400 returns ok and is ready to

take a new instruction. Before entering a command, it

may be necessary to clear the buffer by means of

using

↵.

You need an EDAC 395-010-520-102 connector to

connect the sensor. Please check the EDAC

homepage for details (www.edac.net).

Alternatively the AVX 00 6338 020 000 04 0 or AVX

00 6338 020 000 04 2 connectors can be used to

connect the ASP1400 as well. (See www.farnell.com,

order codes 635789 or 635730).

There is a trade-off between resolution and

measurement time. Possible settings are listed in

Table 2. Choosing 12 bit results in a measurement

interval of 142 ms. With the max resolution of 15.2 bit,

a new measurement is provided every 1280 ms. For

faster sampling rates refer to the ASF1430 high

speed mass flow meter device data sheet.

2.2 RS-232 Interface

All configurations (see also Section 3) for the

ASF1400 can be set using its RS-232 interface). To

communicate with the ASF1400 via RS-232 the

following pins are required:

RxD

(Receiving Data Line)

Table 2: Resolution settings using the res=value

command and corresponding response times

TxD

(Transmitting Data Line)

GND

(Ground)

The RS-232 of the ASF1400 is configured as follows:

Baudrate

9600

Data Bits

Stop Bits

Parity

none

Protocol

none

With these settings, the ASF1400 device can be

connected to any PC or PDA equipped with terminal

software.

res=

Resolution [bit]

data interval [ms]

12.0

142

13.0

284

13.5

427

14.0

569

14.3

711

14.6

853

14.8

995

15.0

1138

15.2

1280

Table 3: Commands of the ASF1400 device.

Command

Output

Description

help

↵

commands

Lists all available commands

www.sensirion.com

Version 2.2

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