Specifications

5.11. Analog Input

The GSM Commander provides a single 0-10V analog input, which can be used to measure

incoming voltages from sensor devices. Using an appropriate resistor, one can also connect

4-20mA sources to the GSM Commander.

What makes this input so special, is that the GSM Commander can interpret the analog value

on your behalf. It is perhaps the best to explain this at the hand of a good example.

Suppose you have a water tank, with a level sensor that is connected to the analog input of

the GSM Commander. The sensor is such, that when the tank is empty, the voltage is 1.2v,

and when the tank is full, the voltage is 7.8v. The configuration software allows you to request

the current reading in a scaled format. You would thus tell the software that 7.8v should

correspond to 5000 litres, and 1.2v should correspond to 0 litres, and leave the rest of the

calculations to the GSM Commander.You can now receive a message from the Commander,

detailing the actual contents of the tank in litres, instead of just a raw value. (Which you would

otherwise have had to convert back to “real” numbers yourself).

Please note that this feature assumes a

linear relationship between the input

voltage and the desired output units.

Thus, this will not work very well for a

cylindrical tank that is mounted on its

side, as the voltage from the level

sensor is not linearly proportional to the

actual contents of the tank.

The user is also able to define the

message to precede, and the message

to follow the analog value.

Please Note: The input is NOT

isolated, and must be used with care.

See the “Advanced Technical manual”

for more detail. (Available on the CD supplied with the product, or on the Internet at:

http://www.gsmcommander.com)

5.12. Battery Input

The GSM Commander provides connections for an external rechargeable 12v battery. The

battery is continuously trickle-charged from the GSM Commander, as long as there is power

supplied to the power connector of the GSM Commander .

In the case of a power failure, the GSM Commander can continue operating from the external

battery. The unit can be configured to perform certain tasks (like sending a warning SMS) if

the battery voltage falls below a certain point, and can also perform tasks in the case of a

power failure. (Like sending an SMS and switching on emergency lighting)

Suitable batteries are available from Polygon Technologies.