Hi
I have two CR1000 communicating through 2 MD485. they send correct data one to the other, but after aproximatly 3 days they fail. the volume of data that i'm sending is quite large and in 2 different periods (a second in both ways and every 10m in both ways also).
Another thing: one of the loggers as to be password protected, so all communication is commanded by one of the loggers (with sendData command and GetDataRecord commands). One of the loggers has 2 serial comunication sensors and 12 single ended signals and the other has 8 single ended signals and a sensor communicating through modbus.
In both sistems i have a CF100 and a 2GB card in which i write all the data, and in both i have a Garmin GPS16X-HVS.
Does anyone has an ideia why my sistem fails?
TaCaPica,
It would be very helpful if you could send us some detailed information about your setup. Please send the following to
gtroberts -a-t- campbellsci ,do-t= com
- OS Version of the datalogger
- Your datalogger programs
- The configuration settings for the MD-485s
- The configuration settings for the datalogger
You can save the configuration settings by connecting with Device Configuration Utility -> Summary -> Save
Does MD485 have internal termination resistences? or do you think that is better to put termination resistences in both MD485?
Another issue, in the same sistem i have 2 sdm-sio1 communicating with 2 sonic 3D wind sensors at 57600 bps (1 at 83m and the other 45m from the logger). Im having some problems getting the serial message from the sensors....do you think that if i use termination resistences i should have a cleanner serial message? the sensors are in half-duplex mode.
Thanks
The MD485 does not have termination resistors. It has transceiver chips that do not normally need them for short to medium cable lengths especially at the baud rates normally used and if using high quality cable.
The SDM-SIO1s use similar chips, but sometimes we have found adding a termination resistor, even at one end of the link, can help when connecting to sensors with less than ideal RS485 cable, e.g. where there is a lot of cross-talk or AC pickup. This is because the resistor acts to kill the noise.