Delta Electronics SS1-UM-1.05 user manual Appendices, Logging the probe as a Linear Quantum Sensor

Appendices

A. Logging the probe as a Linear Quantum Sensor

This application of the SunScan probe turns it into a simple Line Quantum sensor that can be attached to a data logger. No Data Collection Terminal is used, but you do require a data logger that can supply power to the probe when taking readings. The Delta-T DL2e and DL3000 loggers are suitable for this purpose.

If you want to mount the probe on a tripod, a camera mount is provided in the base of the probe handle. The probe's coiled RS232 cable is not used, and it must be protected from moisture by enclosing it in a bag with desiccant, for example.

Note: no batteries are required in the probe for this mode, but it does not hurt to leave them in situ.

Wiring connections

You must use the (optional) special logging cable which plugs into the socket on the probe handle normally occupied by the Beam Fraction sensor. The cable is 10 metres long. If you need more length, simply join on extra screened multicore cable of a similar type. Make sure the joint is weatherproof.

The cores of the probe logging cable have the following functionality:

Core	Function		Logger Connection
orange	V+	Power supply positive	Sensor power positive (switched for warm-up)
green	0V	Power supply negative	Sensor power negative (0V)
brown	HI	Signal output positive	Input channel +
grey	LO	Signal output negative	Input channel -
blue	not used
braid	Screen		Not connected (see below)

Note: the grey, green and braid are connected internally in the probe handle. Connecting the braid to an earthing point on the logger could create earth loops, and is not recommended.

Output

•The output signal is the transmitted PAR irradiance, averaged along the length of the probe. (Individual photodiode readings are not accessible in the Linear Quantum Sensor mode.)

•The millivolt output is linear, with a sensitivity of 1 mV = 1 ∝ mol.m-2.s-1. Maximum output is 2500 mV.

Logger requirements

•The probe requires a voltage supply of 7-15 V dc (unregulated), at about 30 mA current. The analogue output is enabled when the external voltage is greater than the battery voltage.

•Configure one channel of the logger for voltage input, with the above sensitivity.

•Use a "warm-up" time of 1 second (the logger must apply the power 1 second before taking its reading).

•The output voltage will be stable 120 ms after applying external power, and is updated every 60 ms while external power remains connected.

74 • Appendices Document code: SS1-UM-1.05