Checksum (Crc16) - JUMO LOGOSCREEN nt Interface Description

Paperless recorder with tft display, compactflash card and usb interfaces

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4.8 Checksum (CRC16)

Calculation

scheme

Example 1

The checksum (CRC16) serves to recognize transmission errors. If an error is

identified during evaluation, the device concerned does not respond.

CRC = 0xFFFF

CRC = CRC XOR ByteOfMessage

For (1 to 8)

CRC = SHR(CRC)

if (flag shifted right = 1)

then

CRC = CRC XOR 0xA001

while (not all ByteOfMessage processed);

The low byte of the check sum is the first to be transmitted!

Requesting the status of relay output 1.

Instruction: Read a word from the address 0x1631

1631

Response (CRC = 0x8479):

Word 1

Word 1 = 1 indicates that relay 1 is active.

4 Modbus protocol description

0001

D18D

0001

7984

else

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