NORD Drivesystems BU0060 - Manual (Page 49)

4 Communication and Protocol
BU 0060 GB-4112 49
4.2 The CANnord protocol
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4.2.1 Message objects
The control and parameterisation of NORD frequency inverter is implemented via CANnord using four
message objects. The message objects are identified by various identifiers. The following services are
available for a logic master (client):
• Transmit process data (control word and target value) – confirmed or broadcast
• Receive process data (status word and actual value)
• Transmit parameter order (read or write)
• Receive parameter order response identifier / parameter value
• Transfer of setpoint positions with SK 700E with PosiCon option, SK 53xE / SK 54xE
• Transfer of the actual frequency inverter status during operation
Information Communication direction
The data directions "transmit", "receive" are relative to the logic master or client.
The process objects (1. + 2.) can be 4 Bytes (transfer of setpoint) or 8 Bytes (transfer of several
setpoints) long. Parameter objects are always 8 Bytes long.
Information SK 54xE – 2 additional setpoints and actual values
In CAN mode SK 540E and SK 545E devices enable processing of up to 5 setpoints or actual values. However,
this is only possible with a bus configuration via the integrated RJ45 interfaces. For the two additional values, 5
bytes must be transmitted, whereby the 5th byte is a dummy.
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4.2.2 Identifier
The standard CAN (2.0A) permits maximum 2048 different identifiers. Each identifier represents the
address for a message object, whereby a frequency inverter uses at least 4 different message objects.
In addition, so-called broadcast identifiers can be assigned.
The identifier of the message object can be derived from the CANnord address (P515):
Serial No. Message objects Determination of the identifier
1* Process data Master à Frequency inverter (CAN address*2) + 0
2 Process data inverter à Master (CAN address*2) + 1
3 Parameter order Master à Inverter (CAN address*2) + 512
4 Parameter response inverter à Master (CAN address*2) + 513
5 Broadcast process data Master à Inverter 1024 - 1032 (1)
* Only if broadcast is set in frequency inverter
Table 10: CANnord - Determination of message object identifiers
The identifier also specifies the priority in the CANnord protocol (the higher the identifier, the lower the
priority). Process data therefore always automatically have higher priority.
In Extended Frame telegrams, a constant part is added to the identifier. The Extended ID is generated
by adding 18 null bits, so that the identifier for extended and standard formats can be the same. The
identifier format is automatically recognised.
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