Hydrological Services Pty Ltd
Data Logger Model ML1-420
©
Copyright
ML1-420 100-6
Issue 1.00 6 Apr, 2011
3.1 Hardware
Connections
3.1.1 Contact Closure input
The voltage free contact to be monitored should be connected either between Pin 9 (contact
closure input) and Pin 5 (Gnd) with PCB solder link LK1 bridged OR it can be connected
to the internal screwless terminal block, through a cable gland on the enclosure. (
Note
that
the PCB solder link LK1 is an option that is left open circuit when the ML1-420 is supplied
from the factory.) (
Also Note:
In the first option (shown on the left), an extra tip will be
generated when the DB9 connector is plugged into a PC, unless pin 9 is clipped on the DB9
lead.)
Connection of Contact Closure Input
3.1.2 External Power Supply
While the MiniLog ML1-420 is in the field monitoring a 4-20mA transducer, an external 12V
power source
must be
connected to provide power to the transducer. The logger switches the
12V to the transducer, and waits for the preset warmup period (as set by the TXI parameter),
and then measures the 4-20mA current that is passing through the sense resistor. The logger
only uses the internal battery for maintaining the time while there is no external power source
present.
The ML1-420 draws power from the RS232 signals for communications when there is no
external power source present. (Note that this is not sufficient to power a 4-20mA
transducer.)
The internal and external voltage is measured and logged periodically by the logger. The
logging interval is set with the “BVINT” command, which can be set from 1 to 999 minutes.
The logged data can be retrieved with the DUBVI (internal battV) command, DUBVE
(external battV) command, DUBVT (battV and tempC) command or the DUALL (dump All)
command.
While the MiniLog ML1-420 is in the field monitoring the contact closure only, an external
power supply is
not
required. The logger enters a “sleep” mode, waking only to update the
time, and log a contact closure event. In this mode the logger will operate continuously for 2
years on the internal 3.6V lithium battery (or 1 year on a 1.5V alkaline battery).
External
Voltage
Free
Contact
9
5
MiniLog
ML1-420
DB9 pins
LK1
Screwless
terminals
Monitor
Circuit
OR
External
Voltage
Free
Contact
9
5
MiniLog
ML1-420
LK1
Screwless
terminals
Monitor
Circuit
