Campbell Scientific SDM-SIO4 4-Channel Serial I/O Interface - Manual (Page 37)

Section 5. Programming the Datalogger
5-5
Number of invalid commands executed: This is a count from 0-9 and indicates
that the command you have tried to execute is not a current SDM-SIO4
command. Because some dataloggers carry out auto speed detection for the
SDM interface, this counter may be incremented when the program is first
compiled.
Lithium battery level:
0 Lithium battery low and must be replaced.
1 Lithium battery good.
The second floating point value is the same as for Command 1:
Port 4 data available
| Port 3 data available
| | Port 2 data available
| | | Port 1 data available
| | | |
x x x x
If any of these four digits is greater than zero then data is available.
Values per repetition = 2
5.2.7 Command 6: Flush Transmit Buffer
This command flushes the SDM-SIO4 transmit buffer of data it is waiting to
send.
Values per repetition = 0
5.2.8 Command 7: Activate Command Line
This command simulates pressing the push button on the SDM-SIO4 which
activates the command line mode on the port determined by the mode. If the
mode parameter of P113 is 0, the command line will be on the currently defined
port. If the parameter is 1-4, then the command line will be on the port number
specified.
Values per repetition = 0
5.2.9 Command 8: Poll Tx Buffers for Data
This command polls the Tx buffers to see if they have data.
This command has no additional options after the command. The SDM-SIO4
returns one Campbell Scientific floating point number to indicate if it has data
as below:
Port 4 has data
| Port 3 has data
| | Port 2 has data
| | | Port 1 has data
| | | |
x x x x