System bus (CAN) with Servo PLC & Drive PLC
General information
2-14
l
PLC-Systembus EN 1.1
2.6.3
Reading a parameter (example)
Task
Reading the heat sink temperature (C0061) of the controller with the node address 5 via parameter
channel 1.
Telegram to the controller:
Formula
Info
Identifier
= Basic iden node address
= 1536 + 5
=
1541
•
Basic identifier for parameter channel 1 (output) = 1536
•
Node address of the controller = 5
Command code
=
40
hex
•
Command “Read Request”
(Request to read a parameter from the controller)
Index
= 24575 - Lenze code number
= 24575 - 61
= 24514
=
5F C2
hex
•
Code = C0061 (heat sink temperature)
Subindex
=
0
•
Subcode = 0 (no subcode)
Data 1 ... 4
=
0
•
Only read request
11 Bit
8-byte user data
Identifier
Command
Index
Subindex
Data 1
Data 2
Data 3
Data 4
Identifier
Command
code
Low-byte
High-byte
Subindex
Data 1
Data 2
Data 3
Data 4
1541
40
hex
C2
hex
5F
hex
0
0
0
0
0
Identifier = 1541
L
Identifier = 1413
Read Request
(C0061 = ???)
Read Response
(C0061 = 43 ºC)
SDO 1 / Node-ID 5
Telegram from the controller (value of the requested parameter):
Formula
Info
Identifier
= Basic iden node address
= 1408 + 5
=
1413
•
Basic identifier for parameter channel 1 (input) = 1408
•
Node address of the controller = 5
Command code
=
43
hex
•
Command “Read Response”
(Response to the read request with the actual value)
Index
= Index of the read request
Subindex
= Subindex of the read request
Data 1 ... 4
= 43 x 10000
= 430000
=
00 06 8F B0
hex
•
Assumption: The actual heat sink temperature of the controller is 43 ºC,
accordingly, the value of the parameter to be read = 43
•
Fixed32 data format (4 fixed decimal places);
Multiply value by 10000
11 Bit
8-byte user data
Identifier
Command
Index
Subindex
Data 1
Data 2
Data 3
Data 4
Identifier
Command
code
Low-byte
High-byte
Subindex
Data 1
Data 2
Data 3
Data 4
1413
43
hex
C2
hex
5F
hex
0
B0
hex
8F
hex
06
hex
00
hex
(LSB)
(MSB)
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