Biotek BioStack 4 Operator's Manual page 97

Communication Errors
Close the application and try again.
Close one or more other applications that may be using timers.
-5 Invalid request.
The BioStack is not in the correct mode for handling this request.
Restart the BioStack.
-6 Unable to process request.
The BioStack is not in the correct mode for handling this request.
Restart the BioStack.
-401 Object doesn't exist.
This error indicates that the driver software has somehow lost information on
the instrument it is trying to communicate with.
Restart the application.
-504 Unable to open a serial port.
This error indicates that either another application is using the serial port, or
the port was opened either by another application or by the BioStack PC Control
Software, but was not closed properly.
Close the other application.
If that doesn't work, close the BioStack PC Control software and restart it.
Lastly, reboot the PC.
-505 Unable to write all of the serial data.
Try restarting the application.
-506 Timeout while reading in serial data, or incorrect number of serial characters
were read in.
Check the serial cable connection to ensure it is not loose.
Check to see if any other application is very CPU intensive.
Try restarting the application.
-507 Checksum error with the serial data read in.
Attempt the operation again.
Try restarting the application.
-508 When attempting to talk to the instrument, the instrument basecode software
returned a NAK, indicating it did not recognize the request.
Attempt the operation again.
Try restarting the instrument.
Try restarting the application.
-509 PC software received back more data than it was expecting.
Unlikely to be seen. It is expected that a –506 would be sent instead.
Try restarting the application.
Communication Error Codes | 75
BioTek Instruments, Inc.