EM1NR SENSIRION, EM1NR Datasheet - Page 7

• Manufacturer Part Number: EM1NR
• Description: Flow Sensor
• Manufacturer: SENSIRION

Specifications of EM1NR

• Pressure Max: 116psi
• Accuracy: ± 3% At 1-100% Full Scale
• Flow Range: 0-20 Ln/min
• Sensing Accuracy: 3%
• Output Type: RS 232/SPI
• Supply Voltage Max: 18VDC
• Flow Rate Min: 0l/min
• Pressure Drop: 0.29psi
• Supply Voltage Min: 7VDC
• Sensor Output: RS-232/SPI
• Rohs Compliant: Yes
• Flow Rate Max: 20l/min
• Accuracy %: 3%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

CMOSens
2.2 Power supply
The CMOSens
voltage supply between 7V and 18 V. Since this voltage
is internally regulated, there are no stringent
requirements as far as ripple and stability are
concerned.
2.3 Digital Interface
The CMOSens
bidirectional RS232 to set configuration and to get flow
or temperature values. The in earlier versions available
SPI interface is no longer specified, due to changed
specifications of electronic components. If you require
the SPI functionality contact Sensirion.
2.4 Dataformat and Interpretation
The received value is a 16 bit signed integer in the
two's complement representation. The calibrated data
is multiplied by a constant factor and then rounded to
the next smaller integer in order to transfer also
fractions of a unit through the integer protocol.
Product
EM1NH
EM1NL
EM1NR
EM1NV
Example for EM1NV: a received value of +1234 (dec)
corresponds either to 9.641 ln/min in flow mode or
12.34 °C in temperature mode. An explanation of the
overflow modes can be found in section 1.1.
*not possible value, just to show the principle
Figure 6: Interpretation of Integer values
2.5 RS232 Interface
All configurations (see also Section 3) for the
CMOSens
www.sensirion.com
value (hex)
received
0xFFFF
0x87B0
0x7852
0x7851
0x7850
0x0001
0x0000
®
®
Flow scale factor
EM1 Mass Flow Meter for Gases
EM1 can be set using its RS232 interface.
value (dec)
1/100 ml
received
1/50 ml
®
1/128 l
®
1 ml
-30800
30802
30801 peak overflow
30800
EM1 Mass Flow Meter requires a
EM1 Mass Flow Meter has a:
n
-1
/min
n
1
0
n
/min
/min
n
/min
overflow
[ln/min ]
+0.007813
-0.007813
+240.600
0.000000
flow
-240.600
Temp. scale factor
0.01 °C
0.01 °C
0.01 °C
0.01 °C
temperature
[°C]
+308.00*
-308.00*
Data Sheet EM1 – v3.0 /March 2009
--
--
-0.01
0.01
0.00
The following pins are required to communicate with the
CMOSens
RxD
TxD
GND
The RS232 protocol of the CMOSens
configured as follows:
Baudrate
Data Bits
Stop Bits
Parity
Protocol
Echo
With these settings, the CMOSens
connected to any PC or device with an RS232
interface. The commands have to be sent in ASCII
format, the measurement values are provided as a 16
bit signed integer in binary format with 2 bytes
synchronization preceding.
Figure 7: Byte sequence of one value
Because of the maximum range of 0x7852, the high
byte never will contain 0x7F. Therefore the worst case
is, if the lower byte contains 0x7F. In this special case,
0x7F appears three times in a row.
Example (val=7C 7F):
The best approach to find the sync in pseudo code:
if (buffer[ i ]=7F and buffer[i+1]=7F and buffer[i+2] <>
7F)
then buffer[i] and buffer[i+1] are sync bytes.
1. byte 2. byte 3. byte 4. byte
sync
0x7F
(Receiving Data Line)
(Transmitting Data Line)
(Ground)
received string: 7F 7F 7C 7F 7F 7F 7C 7F
right sync:
wrong sync:
®
sync
0x7F
MFM via RS232:
19200
8
1
none
none
the sensor generates an echo
MSB
7F 7F 7C 7F 7F 7F 7C 7F
LSB
7F 7F 7F 7C
®
EM1 device can be
®
MFM is
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