Curtis 3301T, Руководство пользователя

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6 — CANopen COMMUNICATIONS
Curtis Model 3301T Digital Instrumentation – September 2021
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6 — CANopen COMMUNICATIONS
The 3301T complies with the CAN in Automation (CiA) CANopen DS 301 specification. This chapter
describes the 3301T’s CANopen features.
Some familiarity with CANopen is a prerequisite. For CANopen information, see the following pages
on the CiA web site:
• Overview: https://www.can-cia.org/canopen/
• Specifications: https://www.can-cia.org/groups/specifications/
BYTE AND BIT SEQUENCE ORDER
CANopen message byte sequences are transmitted with the least significant byte first (little-
endian format).
Note: This manual uses the LSB 0 Numbering convention when referring to byte and bit numbers.
For example, the following table shows an SDO that writes the data 04E2h to the object with the
index and sub-index 334C-01h:
0 1 2 3 4 5 6 7
Control Byte Index Sub-index Data
2Bh 4Ch 33h 01h E2h 04h 00h 00h
Strings are read from left to right. The following example shows how the 3301T transmits an SDO
segment for the string “3301T-7”:
0 1 2 3 4 5 6 7
Control Byte Data
00h 33h = “3” 33h = “3” 30h = “0” 31h = “1” 54h = “T” 2Dh = “-” 37h = “7”
Bit sequences are transmitted from most significant to least significant bit (big-endian format). The
following example shows how the 3301T transmits the bits for the value 2Bh:
7 6 5 4 3 2 1 0
0 0 1 0 1 0 1 1