20-12-2015, 05:08
Thank you for the pics.
If you need to use a long cable between the sensor and the TX unit, why you haven't chosen a SHT1X family sensor? The SHT2X family sensors use I2C protocol which was designed for communication with very short cables. Hope you have connected the sensor to LI2C port on the TX unit and not simply to the I2C connector. Even using the I2C bus expander chip installed on the TX unit, 9 meters is on the limit of the risk (ideally a second chip should be used at the end of the cable).
We already have talked about this in another topic:
http://www.meteocercal.info/forum/thread...ml#pid3058
As a general advice try to follow this rule: Do your best to use short cables between all the sensors and the TX unit.
Regarding I2C communications, a shielded cable doesn't solve everything, most of the times the problem is the capacitance of the cable which increases with the length.
If you need to use a long cable between the sensor and the TX unit, why you haven't chosen a SHT1X family sensor? The SHT2X family sensors use I2C protocol which was designed for communication with very short cables. Hope you have connected the sensor to LI2C port on the TX unit and not simply to the I2C connector. Even using the I2C bus expander chip installed on the TX unit, 9 meters is on the limit of the risk (ideally a second chip should be used at the end of the cable).
We already have talked about this in another topic:
http://www.meteocercal.info/forum/thread...ml#pid3058
As a general advice try to follow this rule: Do your best to use short cables between all the sensors and the TX unit.
Regarding I2C communications, a shielded cable doesn't solve everything, most of the times the problem is the capacitance of the cable which increases with the length.