06-25-2012 07:17 AM
I started to study with NI 9188 cDAQ and NI 9203 analog input module. I am realy new on DAQ devices and I confused about wiring my pressure transducers to the NI 9203. I want to use 6 pressure transducers whose output signals are ampere (4-20 mA). In the operation manual of NI9203 shows that there is only 1 negative port (COM). Could I wire more than 1 pressure transducers to NI 9203? If it is possible, how could I do this? The pressure transducers that I desired to use has 2 wires and its spec sheet is Emerson PT5.
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06-26-2012 12:46 PM
You can use up to 8 of these pressure transducers with the 9203. Please refer to page 7 of the 9203 Manual.
For the Emerson PT5 specifically, you do not need to use the COM port because you do not have a negative lead. You can wire the signal lead to one of the AI channels on the 9203 and connect the supply lead to an external power supply for 24VDC. Hope this helps!
06-26-2012 01:17 PM
Firstly, thank you for your answer. As far as I know, if we want to measure ampere, we need to wire a sensor to the system serially. If I wire the white cable of the transducer to the NI 9203, do not I need to wire the negative cable of the power supply to the NI9203. I really confused about it. I attached a scheme of wiring transducer to the system. When I want to wire 8 transducers to the system, I need to wire 8 negative cable to complete the system. Am I right on it? But I saw there is just one negative port on NI9203, COM port. I have 24 VDC power supply having two channel + and -, capable of supplying two transducers at the same time. If I want to take measurements from two transducers simultaneously via this power supply, is connecting one negative port of this power supply to the NI9230 negative port (COM) is enough for this job? Thanks in advance.
06-27-2012 08:33 AM
I apologize for the misunderstaning. You do need to wire the negative lead of the power supply to the COM. Your wiring scheme is also correct for one transducer. Please refer to the attached figure to see how to connect multiple transducers. There should only be one negative lead that goes to the COM. Please let me know if there's anything else I can help with. Thanks!
06-27-2012 09:04 AM - edited 06-27-2012 09:13 AM
I am really confused about this. I need to wire 8 PT5 pressure transducers to the NI9203 and I have 4 power supply 24 VDC. I attached a schematic in which the desired wiring scheme is explained. For this purpose, I have to use 4 power supplies having 2 port power output. Could you look at it? If I wire these transducers like in this way would I do wrong?
06-27-2012 11:38 AM - edited 06-27-2012 11:42 AM
The image from the manual implies that you should run all of these sensors from just one power supply. If you use multiple power supplies you will create ground loops which will negatively affect your measurements.
06-27-2012 01:31 PM
Thanks again. In the market, there are just 2 or 3 output 24 VDC power supplies. Once I want to measure ampere from 8 different points via NI 9203, how could address this problem. If I buy 2-output DC power supply I nead 4 pieces of them. Is there any way to connect this transducers to the system with more than one power supplies? Or is there a way like to establish an external electric circuit to do this?
06-29-2012 11:28 AM
You should be able to branch out 8 leads from the one output of the 24VDC power supply. Does this help?