Manual – Starflow QSD Model 6527B and 6537A
Unidata Manual - 6527B and 6537A Starflow QSD User Manual 08 05 2023.docx
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1. OPERATION MODE
There are two modes of operation for the Starflow QSD, SDI-12 and Modbus RTU. SDI-12
operates so that when a Measurement command is sent, the Starflow QSD will Initiate a
read at this time and then provide data after 5 seconds. This allows for power saving as
the rest of the time, the unit is in a sleeping state. When the Unit is in Modbus RTU mode,
measurements are updated every 5 seconds, therefore, consuming more power. This is
required when measurements are required at faster rates. To set the Starflow QSD to
either SDI-12 mode (0) or Modbus mode (5).
1.1. Operation Mode Configuring using SDI-12 protocol
0 = SDI-12
* NOTE 5 = 5 second Modbus scan update or as per how often the Modbus registers are
required to update (5 is the minimum value)
To view the mode of operation, use the following SDI-12 commands.
Example 1 Examine:
Send – 0X8! <CR><LF>
Response – 0+0<CR><LF> (This shows the instrument is in SDI-12 mode).
Example 2 Change:
Send – 0X8+5! <CR><LF>
Response - 0+5<CR><LF> (This changes QSD from SDI-12 mode to Modbus mode)
1.2. Operation Mode Configuring using Modbus RTU protocol
0 = SDI-12
* NOTE 5 = 5 second Modbus scan update or as per how often the Modbus registers are
required to update (5 is the minimum value)
Example: Set Modbus 5 second update (default):
Send - 01 06 00 64 00 05 08 16
Receive - 01 06 00 64 00 05 08 16
