I am integrating a model 3290 Oxygen Analyzer into our equipment, and would like to use the RS-232 port. What documentation can you send me on this analyzer regarding the RS-232 communications? I already have the manual, and while RS-232 is mentioned it does not tell me what the format of any commands or responses is.
- Since it notes that only the "output mode" is implemented can I not send commands to the device?
- Does the device simply start streaming this data to my PC without requesting it?
- The text above states the output is "concentration", but on page 5 of the manual (see below) it specifies "concentration" and "range". So will I be getting two values or only one?
|
What is the recommended flow rate? |
We have a brand new model 3290 that runs for a few hours and then looses its calibration, driving the reading high, shutting down our Nitrogen membrane plant. It read ~6 - 7%, and then the reading went to over 40% Oxygen. It is impossible to be over 21%. We can calibrate it over and over, but it keeps doing the same thing. Why? |
We are technical managers on a vessel equipped with O2 analyzers Model 3290 for IG system. The vessel had problems with the remote indication of O2 content in different locations, when local panel indicates 2.8%, ECR ( Engine Control Room) shows 4.0%, CCR ( Cargo Control Room) shows 3.6% and recorder shows 5.6%. All three instruments are connected in series and show a current of 7.9 milliamps for this reading. There is no calibration method provided in manual. However the local control panel alarm for 5% and 8% O2 are working satisfactorily.
Is there any way to calibrate all these indicators? |
How do you retrofit a 3290 from AC to DC power? |
What is the maximum resistive load on the 4-20mA analog output? |
Can the unit be zeroed?
|
For additional questions, please contact Technical Support.
Q: I am integrating a model 3290 Oxygen Analyzer into our equipment, and would like to use the RS-232 port. What documentation can you send me on this analyzer regarding the RS-232 communications? I already have the manual, and while RS-232 is mentioned it does not tell me what the format of any commands or responses is.
- Since it notes that only the "output mode" is implemented can I not send commands to the device?
- Does the device simply start streaming this data to my PC without requesting it?
- The text above states the output is "concentration", but on page 5 of the manual (see below) it specifies "concentration" and "range". So will I be getting two values or only one?
A: The standard setup is:
Baud: 2400
Parity: None
Data bits: 8
Stop bit: 1
The baud may be changed by removing/installing jumpers on JP6 and JP7.
Available bauds are: 1200, 2400 (default), 9600, 19200.
The 3290 serial communications are output only.
The unit does not accept commands, input characters are ignored/discarded.
During analysis, the uart emits a message consisting of 2 lines each second. The following is an example of 2 sent messages.
O2 = +4.92 %
RANGE = +5.00 %
O2 = +7.30 %
RANGE = +10.00 %
The first line: "O2 = sNN.NN %" is the concentration (where 's' is the sign)
The second line "RANGE = sNN.NN %" is the current range of operation (where 's' is the sign)
The examples show a jump in concentration and the Range is in AUTO mode and changed automatically.
Again, these messages are sent automatically and are not the response to any prompts.
During menu operations, the messages are suppressed.
Back to Top
Q: What is the recommended flow rate?
A: The acceptable flow rate is ~0.1-2.0 SCFH (0.05 - 1.0 SLPM). The vent should be connected to atmosphere, while the inlet will need to be a fraction of a psi above atm pressure, just enough to drive the flow. It is common to use a needle valve and or regulator upstream to reduce process pressure.
Back to Top
Q: We have a brand new model 3290 that runs for a few hours and then looses its calibration, driving the reading high, shutting down our Nitrogen membrane plant. It read ~6 - 7%, and then the reading went to over 40% Oxygen. It is impossible to be over 21%. We can calibrate it over and over, but it keeps doing the same thing. Why?
A: There are several possibilities.
How are you calibrating the sensor? Are you calibrating it in open air or against a standard cylinder of gas? If somehow the cylinder or calibration method is flawed, theses are the results you might get
the other possibility is a damaged sensor (you mentioned earlier it might have frozen?). That might have damaged it somehow, although I would not say it is likely.
It could however, be a generically just bad sensor.
the other possibility is somehow the electronics are damaged or defective.
One other thing to look at is the interconnect wiring. There are four wires from the sensor (two for the sensor itself, and two for the thermistor). If the thermistor wiring is intermittent, it can do exactly what you say happens. This should be checked carefully.
Another possibility is RFI. If there is a strong RFI surge, it can couple into the wiring and cause a spike lasting a second or two.
Back to Top
Q: We are technical managers on a vessel equipped with O2 analyzers Model 3290 for IG system. The vessel had problems with the remote indication of O2 content in different locations, when local panel indicates 2.8%, ECR ( Engine Control Room) shows 4.0%, CCR ( Cargo Control Room) shows 3.6% and recorder shows 5.6%. All three instruments are connected in series and show a current of 7.9 milliamps for this reading. There is no calibration method provided in manual. However the local control panel alarm for 5% and 8% O2 are working satisfactorily.
Is there any way to calibrate all these indicators?
A: The Procedure to calibrate this analyzer can be found on page 4-4, section 4-6 of the instruction manual. A copy of this manual can be downloaded from our website. Here is a link to the a manual section of our website:
man_3290.pdf
Also, greater matching between the displayed valued on the LED display and the analog output can be made by narrowing the range of the analyzer. The analyzer comes with two user programmable ranges.
For instance on a range of 10 percent, the typical matching error on the analog output is typically 1 per cent of scale or less of scale, which is plus or minus 0.1 percent of O2.
If intstead the range is set to say 2 percent, then the matching error is 0.02 per cent O2 plus or minus.
Back to Top
Q: How do you retrofit a 3290 from AC to DC power?
A: Please refer to the following instructions: retrofit_3190_3290_AC_to_DC.pdf
Back to Top
Q: What is the maximum resistive load on the 4-20mA analog output?
A: Maximum resistive load is 500 ohms.
Back to Top
Q: Can the unit be zeroed?
A: Although not recommended, a gas zero can be performed by pressing the HI ALARM and LO ALARM buttons at the same time.
Back to Top
