diff --git a/docs/DS18x20.md b/docs/DS18x20.md index 156b774efd..fb50dd4a84 100644 --- a/docs/DS18x20.md +++ b/docs/DS18x20.md @@ -32,7 +32,15 @@ Sensor sends a `tele/%topic%/SENSOR` JSON reponse: [`TempOffset`](Commands.md#tempoffset) can be used for calibrating the measured temperature. This setting affects **all** temperature sensors on the device. ### Multiple Sensors -Tasmota supports multiple DS18b20 sensors connected to a single ESP8266 chip. At this time, the maximum is set to 8 (see #define DS18X20_MAX_SENSORS 8 in https://github.com/arendst/Tasmota/blob/development/tasmota/xsns_05_ds18x20.ino#L40 ) +Tasmota supports multiple DS18x20 sensors connected to a single ESP8266 chip using a single GPIO (multiple DS18x20 GPIO are not supported). The default maximum is set to 8 ([driver code](https://github.com/arendst/Tasmota/blob/development/tasmota/xsns_05_ds18x20.ino#L42)). It is possible to override this number in `user_config_override.h` by adding a line with `#define DS18X20_MAX_SENSORS ` (ESP8266 only). However one should take into account that: + +* Display on the console is limited and SENSOR log will be truncated above 11 DS18x20. +* MQTT buffer length is limited and SENSOR message will be truncated above 18 DS18x20. +* Even less if other sensors are attached to the ESP device and present in the SENSOR message. +* 1-wire has been designed to be a board-bus, not to run through long distances across a whole house. At minimum, use a shielded cable. + +!!! note + If you increase the value above default, you are on your own. No support will be provided. ![multiple wiring](https://user-images.githubusercontent.com/5904370/68093672-4b1a2700-fe98-11e9-8c63-3a9b566546b5.png)