Brooks Instrument BM50 - Manual (Page 35)

3-11
Section 3 Operation
BM Oval Series
Installation and Operation Manual
X-PD-BM-Ovals-eng
Part Number: 541B031AAG
January, 2009
Remarks Terminal Connectors:
Terminal 1-3; Flowmeter Inputs
The pulse has to be connected to terminal 2. The screen of the signal wire
must be connected to terminal 3 (GND). The voltage supply (3.2 Vdc) to
the flowmeter should be connected to terminal 4. Please read par. 4.2. for
power supply flowmeter. The maximum input frequency is approximately 7
kHz (depending on the type of signal see Section 3.2.3.5).
Pulse-signal NPN/PNP:
The Standard Display is suitable for flowmeters which have a pulse output
that is equal or almost equal to the supply voltage (3.2 Vdc). For a reliable
detection, the pulse amplitude has to cross 1.2 Vdc once per cycle.
Transducers which generate a higher amplitude than 3.2 Vdc can be used
but the detection level is still 1.2 Vdc. Maximum voltage input is rated for
pulse amplitudes of 24 Vdc.
Reed-switch:
The Standard Display is suitable for flowmeters which have a reed-switch.
To avoid pulse bounce from the reed-switch, it is advised to select REED
LP - low-pass filter (setting 51).
Terminal 4 and 5; external power supply 8-30 Vdc:
Connect an external power-supply of maximum 30 Vdc to these terminals.
Connect the “-” to terminal 5 and the “+” to terminal 4. The output voltage
from the battery (option) is blocked automatically as soon as a higher input
voltage than 3.2 Vdc is connected: it won’t damage the battery.
Figure 3-5 Pulse-Signal NPN/PNP
Figure 3-6 Reed-Switch