Specifications

7. APPENDIX
Page 89 ©2001~2007 DH Instruments, a Fluke Company
• To convert an electrical measurement into a flow unit MFC-CB first follows the
regular electrical value to display calculation (see Section 7.1.1) and then converts the
electri
cal value into a flow value. The conversion of an electrical value into a flow value is
made following:
()
0,
,
0
MM
M
MMM
EFS
FFS
EF
−
⋅−=
Where:
M
F
= Displayed flow measured value
M
E
= Displayed electrical measured value
M
0
= Electrical value corresponding to zero flow
M
FS,E
= Electrical value output corresponding to full scale flow
M
FS,F
= Full scale flow value
For example, if the MFC profile specifies a 4 to 20 mA electrical range and a 500 sccm
FS flow range, a reading of 12 mA is converted to a flow value following:
()
][250
][4][20
][500
][4][12 sccm
mAmA
sccm
mAmAM
F
=
−
⋅−=
7.2 DEVICE CHANNEL CONNECTORS AND CABLES
Use Table 13 to wire the interfacing cable required to connect an MFC-CB DEV1 or DEV2 connector
to an MFC or MFM. Section 7.2.1 provides information on some common MFC cable setups.
Table 13. MFC-CB DEV1
and DEV2 Connector Pin Out
MFC-CB DEV1, DEV2
25 PIN DSUB
CONNECTOR PIN NO. SIGNAL SIGNAL DESCRIPTION
1
Case Ground Earth ground for shielding.
2
Supply Common
Ground line for the MFC’s power
connection. It is frequently referred to as
“Power Common”, “Supply Common”, or
just “Common”.
3
MFC Measure (+)
Positive Voltage signal that represents the
MFC’s measure. It is commonly referred
to as “output” or “signal output”.
4
+15 Volts Positive MFC or MFM supply.
5
N/C No connection, no signal.
6
N/C No connection, no signal.
7
Set Point Sense (-)
Ground reference for the MFC set point
sense. It should be connected to the
same point as the MFC set point (-) line.
8
N/C No connection, no signal.
9
N/C No connection, no signal.
10
N/C No connection, no signal.