Modbus Parameter Specifications

MODBUS ACE V1.00
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ebm-papst Mulfingen GmbH & Co. KG
Bachmühle 2 ·74673 Mulfingen ·Phone: [phone] ·Fax: [phone] ·www.ebmpapst.com ·[e-mail]
DocNo.: 634505DocNo: 446144DocNo.:358982DocNo.:322523DocNo.:309753DocNo.:303997DocNo.:276241DocNo.:256078DocNo.:196392 ·Template: 2 dated 10/6/2003 ·File: ext001931381.docx ·Last printed 9/30/2019 10:29:00
AM ·Page 23 of 78
Form 1003
Procedure:
On setting up the installation, the fans must be arranged in the ascending order of their serial numbers. This is
necessary to ensure simple assignment of the automatically allocated MODBUS addresses to the fans in the
installation.
To start with, all fans are set to the MODBUS address 0x01.
2 broadcast commands are required for this:
 Set holding register fan address (D100) to 0x01: 00 06 D1 00 00 01 CS CS
(CS = CRC checksum)
 Set holding register reset (D000) to 0x02 Transfer parameter: 00 06 D0 00 00 02 CS CS
All the serial numbers of the installation are determined in a loop:
The mask for serial number addressing is first set to Broadcast addressing
(00 00 00 00 00 00). The last byte is set to the start value 0x30 (0).
The mask SerNo is thus 00 00 00 00 00 30.
This mask is used to search for fans with the value 0x30 (0) at the last position of the serial number.
Use can be made of any command for reading a holding register or input register, e.g. Read holding register
fan address: 01 43 00 00 00 00 00 30 D1 00 00 01 CS CS
There are several possible outcomes for the response:
 An unequivocal response:
The fan responds with its serial number (SerNoFan) in the address field.
This serial number is stored in a list.
The fan is then blocked for further requests by setting the MODBUS address to 0xF7 (247).
The same serial number then has to be polled again, as there is a possibility that a further fan may also
have been addressed but did not respond as it had already detected the start of the response of the other
fan on account of differences in runtime.
 An invalid response due to overlaid responses from several fans:
The serial number mask then has to be further restricted by also setting the penultimate byte to the start
value 0x30 (0). Only fans with the value 0x30 (0) at the last two positions of the serial number will then
respond to the next request.
 No response:
All serial numbers with the value 0x30 at the last position can then be excluded. The last byte of the mask
is incremented to the value 0x31 (1). All fans with the value 0x31 (1) at the last position of the serial
number will then respond on next polling.
The loop is continued until all serial numbers have been polled:
 In the event of a valid response, the serial number of the fan is stored in the list
 In the event of an invalid response, the serial number range is further restricted by masking another byte,
commencing with the start value. For the last 4 bytes the start value is 0x30 (0). The first two bytes have
a start value of 0x01, as the year (2001) and week (W1) are coded here.
 If there is no response, the position concerned is incremented by 1 until the end value is reached.
For the last 4 bytes the end value is 0x5A (Z). For the first byte (year), the end value is 0x63 (2099); for
the second byte (W), the end value is 0x35 (W53).
Once the end value has been reached, the position concerned is addressed again by way of broadcast
addressing (0x00) and the next position is incremented by 1. When the addressing for the last byte
reaches the end value 0x5A (Z), all serial numbers have been checked. The polling of serial numbers can
thus be concluded.