Campbell Scientific MD9 Coax Multidrop Interface - Manual (Page 11)

MD9 Multidrop Interface
7
now complete. The computer can now send several carriage returns which
permits the datalogger to synchronize at the same baud rate.
Once the datalogger baud rate has been synchronized, data retrieval, data
monitoring and re-programming of the datalogger can be carried out.
To terminate communications with a datalogger, use the E command (followed
by a carriage return) listed in the datalogger instruction manual. The datalogger
will respond by lowering the ME line to its MD9 causing it to return to State 0.
In order to activate the next datalogger station, a BREAK and the next
ADDRESS is sent by the computer. This procedure continues until all
dataloggers in a network have been interrogated.
When all data for a particular time period has been collected and stored by the
computer, the computer's DTR line is released causing the local MD9 to return
to State 0.
An MD9 used in the telephone conversion must be operated in the "Protocol
Mode". In the Protocol Mode, the MD9 communicates with the computer via
the phone and controls activity on the coax network generating the "Break"
command, etc. The Protocol Mode is activated when the MD9 ID switch is set
to 255 (all switches OPEN).
When a station file is set up using PC208 software and the MD9 is not entered
as the FIRST "Interface Device", the software assumes the MD9 at the phone
modem is in the Protocol Mode.
If both conditions are met the MD9 ID set to 255 and the MD9 is not the first
Interface Device the telephone to MD9 conversion is transparent to the user.