User manual

CS475, CS476, and CS477 Radar Water Level Sensor
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8.1.2 Check Unit Response
The Acknowledge Active command is used to check the presence of the sensor on
the bus (see Table 8-2).
Table 8-2. Acknowledge Active Command
Initial Command Response
a!
a<cr><If!>
Only the address is sent back in response.
8.1.3 Check for Valid Data
The aI! command gets the following identification information in response to
sending aI! (see Table 8-3).
• Compatibility level: Version of SDI-12 protocol version; for example, 1.3.
• Manufacturer’s Name: VEGA
• Manufacturer’s Model Number: PS61 (CS475), PS62 (CS476), or PS63
(CS477)
• Three Digit Firmware Version Number.
• Eight Digit Serial Number of Sensor.
Table 8-3. Send Identification Command
Initial Command Response
aI! a13VEGAbbbbPS6233212345678<cr><If>
Where (from left to right),
a—sensor address;
13—SDI-12 compatibility number;
VEGA = Manufacturer’s Name;
PS62 = Manufacturer’s Model Number;
3.32 = Sensor Version Number;
Serial Number = 12345678.
8.1.4 Cyclic Redundancy Check
A cyclic redundancy check (CRC) is used to produce and send a small, fixed-size
checksum of a larger block of data to the datalogger. This checksum detects errors
after transmission or storage. The CRC is computed and added before any
transmission or storage. The CRC is also authenticated by the recipient, after the
transmission, to confirm that no alterations occurred. CRCs are very good at
identifying errors caused by noise in transmission channels.
8.1.4.1 Check CRC for Valid Data
The aV! command requests three verification values from the sensor. This
command is always followed by the aD0! (Send Data) command.