Hello,
I bought the 2091-EVKITSWF-20-ND for testing CO2 flow air in my work. It was working normally for approximately one year, until recently, when the signal displayed in the GSS Sensing software began to become intermittent. The software also occasionally displays unusual letters or corrupted characters, which may indicate a communication error (attached images).
When I introduce CO₂ gas to the sensor, the software does not detect any change in the CO₂ concentration. The sensor has not been dropped or subjected to any physical impact, so I do not believe that the sensor itself has been damaged in this way.
Could the communication cable be causing this problem? Could you please advise me on how to determine whether the problem is caused by the cable, the 4-pin connector, or the sensor itself? Would replacing the cable be an appropriate troubleshooting step?
Thank you
Greetings,
A year is a fairly long time for a device wrought as an evaluation kit; damage due to static discharge is more of a when than an if for an exposed PCB, and the 0.1" connectors aren’t exactly a high-durability item.
A bad connection could easily explain garbled data though. Visual inspection of the board, connectors etc. would be cheap and easy enough. Changes that occur when pressure is applied can offer clues. Wires breaks inside the insulation do happen, and can be rather troublesome to identify. Attached datasheet indicates that the sensor responds with a question mark to unrecognized commands and it seems those are coming through fairly well, so the line transmitting to the board might be a good thing to look at first.
Pulling out an o-scope and looking at the waveforms would be a more direct diagnostic approach, though it does require some familiarity with the subject matter.
Replacement cables don’t seem to be available from the supplier, but something like the TTL-234X-3V3-WE might possibly be made to work.
SprintIR-W.pdf (717.1 KB)
Hi Rick,
Thank you for the response.
So it means I need to purchase a new cable and should work properly again right? Could you confirm for me that the cable TTL-234X-3V3-WE will be a posible replacement for my case?
Thank you.
Negative: without identifying the cause of the problem, no assurance of a potential solution’s viability can be made. If anything, I would expect the cable to be the least likely source of difficulty.
In the event that it is at fault, the cable part number mentioned is a USB-UART type operating at a 3.3v level, which would appear to appear to be suitable for the interfacing to the sensor generally, such as using a terminal program of your choice. Whether or not the supplier’s evaluation software would play nicely with it is a different question, on which I don’t have enough info to offer comment.
Hi Rick,
Thank you for the response.
My goal is to test CO2 ppm from the outlet air for my experiment. I’m not an electronics person and we don’t have equipment to carried out o-scope. So is there other simpler way I can check whether the sensor board or the cable is the problem? Such as multimeter?
In the meantime, I plan to purchase the cable TTL-234X-3V3-WE and check with the sensor board.
Also I have another question, will it be possible to replace with other cable, for example the 954 Adafruit Industries LLC | Smart Cables | DigiKey ? Because we cannot make the 4-pin housing if we purchase the TTL-234X-3V3-WE, so we prefer a complete cable.
Thank you.
Not being an electronics person tends to complicate electronics troubleshooting significantly. I suspect there are a number of people within your organization that could assist, and the time/frustration saved would likely be worth the cost of asking.
I would not suggest the Adafruit cable for use with the sensor in question, because it is designed with different power and logic output levels that may cause unreliable operation unless inconvenient measures are taken.
Unneeded signals provided by the cable suggested may simply be left unused, and connector housings such as the 952-2229-ND are readily available. (Contacts below on the page, crimp tool needed.) Alternatively, the connectorized version (remove the -WE from the part number) could have the pin-out re-arranged to suit with some care.
Simply replacing the entire kit may be a good option at this point; it’s a guaranteed fix, and where you’ll end up anyhow in the event that the board is indeed damaged.
Hi Rick,
Thank you for your suggestion.
I also look up all the cables in USB to TTL series. I notice there is one similar to TTL-234X-3V3-WE, which is TTL-232RG-VREG3V3-WE FTDI, Future Technology Devices International Ltd | Smart Cables | DigiKey.
The only difference that I understand is 50mA and 250mA. Is it mean that the 250mA will have more headroom than 50mA? Is the TTL-232RG-VREG3V3-WE FTDI, Future Technology Devices International Ltd | Smart Cables | DigiKey suitable as the replacement cable for my eval kit?
Thank you.
At this point I would recommend disregarding all discussion of cable replacement, and purchasing a replacement kit.
As mentioned, the cable itself may not be at fault and any alternative devices one may try are not assured to be functional with the system in question.
