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CS475, CS476, and CS477 Radar Water Level Sensor

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<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.

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Campbell CS475 Bedienungsanleitung Seite 32