MODBUS LITE V5.01 parameter specification

MODBUS parameters "ebm-papst series 84 / 112 / 150 / 200"
_______________________________________________________________________________________
ebm-papst Mulfingen GmbH & Co. KG
Bachmühle 2 ·74673 Mulfingen, Germany ·Phone: [phone] ·Fax: [phone] ·www.ebmpapst.com ·[e-mail]
DocNo.: 634505DocNo.: 446144DocNo.:358982DocNo.:322523DocNo.:309753DocNo.:303997DocNo.:276241DocNo.:256078DocNo.:196392 ·Template: 2 dated 6 October 2003 ·File: ext001157859.doc ·Last printed 10/03/2015 15:13:00
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Form 1003
CRC L / CRC H
A CRC checksum is generated for the complete telegram.
The polynomial for defining the checksum is 1 + x
2
+ x
15
+ x
16
(i.e. XOR operation on 0xA001).
The initial value is 0xFFFF.
The low byte of the checksum is transmitted first, then the high byte.
More detailed information about calculating the checksum can be found in the "MODBUS over Serial Line
Specification & Implementation guide V1.0".
1.2.2 Response from fan
A fan will only respond if
 it receives a message sent to its own address;
for the broadcast address, no response is sent.
 the telegram length is at most 23 bytes.
 the correct number of data bytes was sent so that the telegram can be interpreted.
 the checksum was correctly recognised.
Initial synchronisation:
After the command from the master has been completed, the fan will wait for at least one transmission pause
of 3.5 bytes. Depending on the command and on the processing time, the pause may be much longer (until
the fan has received all the data it has requested)
Address:
The address is repeated by the command from the master (i.e. its own fan address)
Command:
If the command can be processed, the command code will be repeated.
If the command cannot be processed, the fan will respond with an exception.
Here, the MSB is set to command.
The command byte is then, for example, 0x83 for the command "Read holding register (0x03)".
Data:
Depending on the command concerned, the number of data bytes and their meaning may differ.
Please refer to 1.3 Commands.
CRC L / CRC H
A CRC checksum is generated for the complete telegram.
The way the checksum is generated is no different from the procedure described above for the command from
the master.