TRIGGER INPUTS
There is trigger input D1. This can be used to control desludge and other functions see programming section. The digital trigger input is connected as shown below:
5V 
10
D1 
8
0V 
7
A voltage greater than 2V on Terminal 8 (D1) causes trigger input 1 to be active. This can be achieved by connecting to terminal 10 (5V) via an external switch or relay. The maximum voltage should not exceed 28V.
24V 
MES*AI OR
ELECTRO SENSOR
0V
24V
25
0V
26
D1
8
0V
7
The trigger input is also compatible with the MOBREY Electrosensor sensors and head amplifiers. A 24V output is provided for this purpose. Typically this allows complete control of the desludge cycle by using a second sensor (Electrosensor) to start or stop the cycle. The terminal connections are shown above (note: it is important that the two 0V connections on terminals 7 and 26 are linked).
NOTE : When connected to these terminals the electrosensor sensors and head amplifiers MUST NOT be installed in explosive atmospheres.
MAINS SUPPLY
The unit can be powered either by 24V DC or by mains AC power. If both are connected, the unit will select the supply producing the highest internal 24V power rail. Select the AC Voltage as 115V or 230V using the selector slide switch above the AC line terminals.
Although the MSM400 meets all European standards for surge immunity on power and signal lines, it is recommended that lightning suppressors are fitted if local conditions make this advisable. Units manufactured by Telematic are suitable.
SAFETY PRECAUTIONS
A switch or circuit breaker should be installed in close proximity to the instrument, and labelled as such.
The unit must be earthed using the protective earth terminal 31.
INITIAL POWER UP
The unit will initially display the software revision number on Power up, and then revert to the standard display screen, showing a measured slurry/sludge density. If the sensor is in air, then this value will be high
effectively at full scale deflection.
IP258
15
