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The SSP uses analog input channels 1 through 6, and digital channels 1 through 8. These channels
are indicated with a heavy border on the terminal block legend, and cannot be used to connect
external sensors to the logger while the SSP is attached.
Analog channels 7 through 12, digital channels 9 through 16 and the serial data channel are not used
by the SSP, and therefore can be used to connect external sensors to the logger while the SSP is
attached.
It is suggested that you connect the thermocouple originally supplied with the DT800 to analog input
channel 6 to complete the sensor set.
4.
Powering the SSP
Several of the sensors and actuators on the SSP require power, which is supplied by the DT800. Two
power supplies are used, the 5 VDC sensor power supply provided on terminal
Sp
, and the 12VDC
serial data channel power supply provided on terminal
Serial 12V
.
These power supplies are turned on by the DT800 commands
P47=5
1SSPWR=1
Most of the sensors and actuators require one or other of the power supplies, however it is simplest to
always have both power supplies enabled at all times when using the SSP.
These two commands can be entered directly into DeTransfer text programs. In DeLogger4 the
parameter command can be set in the DT800 program builder and click on the Parameter tab. The
P47 value can be changed by clicking on the down arrow and selecting one of the values
Fig. 9.
The sensor power value should be set by clicking on the Immediate tab in the DT800 program builder
window. Then enter a User channel type and typing in the serial sensor power command.
Fig. 10.
Note:
If you send a RESET or FORMAT command or perform a push button reset at any time while
using the SSP, this will turn these power supplies off and so affect the function of powered sensors
and actuators.
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