EBME Forums Forums Maintenance Technical Assistance Mainstream ETCO2 Sensor CM2200 / Capnostat 5

Hello!

I am programming a monitoring device for an e-health research project. It does CO2 measurements.

As mentioned in the title, two CO2 sensors are used: CM2200 and Capnostat 5. Both sensors have to be using the same protocol since my code works for both identically. Specification with protocol description is attached and available here in Google drive: https://drive.google.com/file/d/1EMyQ6AMnBkjyrwkzUrEWe8IEAgXwJf43/view?usp=share_link).

I have a problem with ETCO2 and respiratory rate (RR) readings. After a successful zeroing procedure, ETCO2 and RR values are always zeros when I continuously breathe into the sensor.

Could that be related to the sensor not being connected to the breathing mask and system at both ends? Only this airway adapter is inserted into the sensor:



Does anyone know what could cause such behavior?
Any help or tips are very appreciated! : )

How are you communicating with the sensor?

Can you effect a Reset ... and obtain any error codes?

Do you have a spec sheet for the Capnostat 5?

How are you communicating with the sensor?
- Via serial port. It is directly connected to the device (Arduino) that I am programming.

Can you effect a Reset ... and obtain any error codes?
- I have tried doing a hardware reset and software reset (sending command sequence). In both cases no error code.

Do you have a spec sheet for the Capnostat 5?
- Not right now. It looks like the spec sheet is not publicly available since it is not listed in the documents on the manufacturer’s website (https://www.hamilton-medical.com/en...ory=all&tab=all&resource-lang=en). I will contact them and post an update here.

It's difficult to comment further without full information about your setup (and code etc.).

But do you see anything (signal) at pin 5 when the sensor is powered and you breathe through it?

If the sensor responds, then the problem must be at "your end". I would start by checking (confirming) communication protocols.

Good Luck!

Thank you very much for the replies Geoff!

It's difficult to comment further without full information about your setup (and code etc.).
- Of course, I understand. Unfortunately, right now, I can not share the code. That is why I am asking for any tips or ideas ... Always worth trying ...

But do you see anything (signal) at pin 5 when the sensor is powered and you breathe through it?
- Yes, the sensor is working correctly. When I switch it on, it does the zeroing procedure and continuously sends CO2, end-tidal CO2, and respiratory rate measurements. The problem is that while CO2 values look good (see image), end-tidal CO2 and respiratory rate values are always zeros.

You can see the zeroing procedure on the graph’s left side.



If the sensor responds, then the problem must be at "your end". I would start by checking (confirming) communication protocols.
- That is exactly what I have been doing for the last few days while waiting for Capnostat specification.

I have the same problem, the EtCO2, RespRate and InspCO2 [2, 3, 4] appear as zeroes, each 1.000ms. And DPI#5, BreathDetFlag, never appears. I had tried the command ResetNoBreathDetFlag [CCh], unsuccessfuly.

Anybody has the Capnostat5 or lower datasheet ?

I contacted the manufacturers, and unfortunately, they refused to provide specifications/datasheets for students (requesting those docs as a student is the only option I have).

Hello, I have novametrix 8100 COsmo service manual, it includes Capnostat electronic test and circuits full explained , as this: "Also located on the input buffer IC13 are the CAPNOSTAT CO2XDISC,
CO2ZERO* and CO2SPAN* signals, which inform the system that a CAPNOSTAT sensor is
disconnected, if it is connected and currently on the Zero Cell, or if it is connected and currently on the
Reference Cell."
here is link
https://mega.nz/file/WN12ASwL#xk-YiX3wV-1CUibP846BcfGiitly44KCdXnMDcK-I4E

Officially, I'm a graduate student, I just contacted them and right now I'm waiting for the specialists to come back, they said to wait for that. Let´s see...