Hi,
I have to connect around 10 of the CS457 conductivity probes to a system.
In the manual are writen
"The exitation channel used for EC must be seperate from the one use for temperatuer or measurement errors will result".
In my way of unserstanding this is due to the parallel electrical resistors of both sensors.
But, it´possible to connect a couple of T107 to one exitation channel!
What I planed to do, is to proceed FullBridge measurement at the AM16/32 with the attached CS457 (via as 457!!).
Or is ther another way to take measurements of 10 conductivity probes using a CR1000 with a AM16/32.
Thanks in advance
Heiko
Seems to me that you would
Wire the "datalogger terminals" of the A547 to the logger as shown in the manual in Figure 4-1.
Wire the "sensor terminals" of the A547 to the "COM terminals" of a AM16/32B configured for 4x16 mode.
Odd H --> Ex Temp
Odd L --> Temp
Even H --> Ex Cond
Even L --> Cond
Ground --> Shield
Wire the 10 CS547A's to 10 of the SET inputs on the AM16/32B (4x16 mode).
1H --> Sensor 1, Ex Temp
1L --> Sensor 1, Temp
2H --> Sensor 1, Ex Cond
2L --> Sensor 1, Cond
Ground --> Shield
3H --> Sensor 2, Ex Temp
3L --> Sensor 2, Temp
4H --> Sensor 2, Ex Cond
4L --> Sensor 2, Cond
Ground --> Shield
Sam's advice is good.
To explain the statement in the manual for you, we would not advise connecting the conductivity and temperature measurements to the same channel because the conductivity sensor is a variable load on the excitation channel both in resistance and capacitance terms.
Whilst the excitation channels can deal with the variation in load to give a reasonable conductivity measurement, the time taken for the excitation output to stabilise at the start of the measurement can be quite long and vary.
Our standard instructions for measuring the T107 temperature sensor are designed to make quite a fast measurement and will give good results with 107 thermistors with low capacitance wiring. However, if the excitation channel used, is also driving a large capacitative load such as the conductivity sensor, the excitaiton and therefore the sensor output may not settle before the measurement is made, resulting in errors.
* Last updated by: aps on 1/10/2012 @ 4:27 AM *