KC868-Server Modbus Long Distance

[v1rtus]

Hi,

I have a KC868-Server module, and a few Temperature and Humidity Sensors (XY-MD01). Everything works find when connection cable is short or when there is only one sensor connected via long cable ( a few meters).
However when I connection more that one sensors via long cable, sensors either do not work at all or some of them work time to time.
Any ideas?

Thank you in advance!

[admin]

is this sensor use by RS485 interface?

[v1rtus]

Yes, the sensor is working on RS485 interface, and works well when only one connected or when more but with short cable length.

[admin]

you can use CAT5 cable. how long distance your board can't work?
do you use KC868-Server conenct with only one RS485 sensor?

[v1rtus]

I use CAT6 cable, the cable length is different. I have 7 sensor in a house, and cable length can be up to 15 meter but in most cases less. Yes only sensors are connected to orange input on KC868-Server.

[admin]

you ask you, when your problem whether test by only one sensor? do you understand me?

[v1rtus]

1 sensor connected to RS485 - everything works fine, cable length does not matter
2 or more sensors connected with short cable length - everything works well
2 or more sensors connected with long cable length - does not work on values can be read on rare cases

[admin]

The last RS485 "SLAVE" device needs to be connected in parallel with a 120 ohm terminal resistor on the bus, do you have added it?

[v1rtus]

thank you for the advice, I forgot to put termination resistors to the both ends. Now it works, however reading is not stable, pretty often it returns CRC Error any idea?

[admin]

check your wire, you can test with short wire distance, whether work well, or only error in long distance.