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Post by leethargo on Oct 21, 2023 20:10:53 GMT
The METER module that I added to my starter rack 2 seems to work OK and reliably in all different modes, except for one thing: When I patch a 5V to the input, and select the VOLTMETER mode, it displays a value of 4.16 or 4.17V, and not the expected 5V. I tried connecting the 5V that is available on the module itself, or from the MASTER module, which gives the same result. I worried that the voltage would have dropped to 4.17V already when reaching this module, so I now borrowed an external multi-meter but this shows the expected 5V when I compare the 5V and GND from MASTER, or also some 5V output (here: NAND from LOGIC) from far away module with GND from MASTER. Finally, I verified that 5V is also reached in the bottom row for micro modules. So my questions: Is this a known issue with the VOLTMETER mode? Does this require some calibration? Is it a symptom for some other underlying issue? I can tolerate the low values in METER as it functions well otherwise and I mostly use the oscilloscopes, but I wanted to rule out some other issues. I'm happy to run some more experiments with the multimeter in the next days (before I return it).
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Post by leethargo on Oct 21, 2023 20:11:34 GMT
Another test where I use the 5V from MASTER directly:
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Post by leethargo on Oct 21, 2023 20:12:41 GMT
Measurements with the multimeter, first at METER's 5V, comparing with MASTER's GND, which shows 4.86V (so neither 5V nor 4.17V): Then with an output from LOGIC (far away module along the bus cable), which is quite close to 5V, even though the module is placed "behind" METER along the bus cable.
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Post by robertlanger on Oct 22, 2023 11:59:35 GMT
Thanks for sharing your observation! Let me check it in the HW design and firmware; then I can answer this correctly!
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