What might cause error messages such as “transaction failure” and “unreachable destination” when trying to connect a datalogger and a PC using a serial or USB to RS-232 cable?
Some possible causes include the following:
- The result of a hardware condition in the datalogger or the port driver
- Incorrect USB drivers (Even if the correct drivers have been successfully installed, the errors may still be related to the cable.)
- Note: Not all USB-to-serial cables are the same. Although any USB to RS-232 cable should work with the appropriate drivers, there is a better chance of success using the USB to RS-232 cables sold by Campbell Scientific. Cables that are not purchased from Campbell Scientific have not been tested and may result in errors when connecting to a datalogger. Furthermore, USB-to-serial cables with the FTDI chipset are easier to use and seem to perform better than cables with the Prolific chipset.
- Power supply or grounding issues on the datalogger
- The port configuration of the datalogger (If the datalogger RS-232 port is configured at a fixed baud rate other than 115200, it might cause the error messages.)
The Device Configuration Utility, under its Unknown device type, has an Identify Logger Type button. This button will attempt to identify the device type, protocol, or both used for the datalogger and will attempt to do so at various baud rates. If the datalogger is synchronized with a different baud rate or is set up at a fixed baud rate, this feature may provide the means of determining what baud rate should be used for successful communication.