HS6M 6
CANOpen Protocol “C”
The CANOpen protocol provides a set of data bits inside a CANOpen
message that represent the encoder position (in turns and within 1
turn).
CANOpen may be wired in several different configurations, but the
most common is a “Trunk and Drop Line” configuration. The trunk
message cable must be terminated at each end with 120 ohm
resistors. Note that CANOpen also offers the option to carry device
power to each encoder through an additional cable pair of wires.
Preferred cable: Twisted pair with individual pair and overall shields.
Communication pair: 24 AWG, copper conductor, capacitance of
50 pF/meter (15 pF/foot) terminated in a 120 Ohm resistive load.
Power pair: 22AWG copper conductor, 17ohms/1000 ft [55 ohms/
km]. Note that resistive losses in long cables may decrease actual
voltage (+Vs) available at the encoder; larger conductors can be
used or the encoder can be powered locally and signal GND brought
through the cable. Maximum transmission speed is limited by cable
length and number of devices as shown in the figures below.
Nidec-Avtron recommends the use of a simple no-cost debugging
tool such as PCAN View.
For more details on CANOpen, consult the CiA, CANOpen in
Automation:
www.can-cia.org
Network
Baud
Rate
1M
500K
250K
125K
50K
20K
Units
Max.
Length
65
[20]
325
[100]
800
[250]
1600
[500]
3250
[1000]
8200
[2500]
ft
[m]
Max.
Single
Tap
Length
1
[0.3]
15
[5]
15
[5]
15
[5]
200
[60]
500
[150]
ft
[m]
Max.
Total Tap
Length
5
[1.5]
100
[30]
200
[60]
400
[120]
1000
[300]
2500
[750]
ft
[m]
Min. Tap
to Tap
Length
-
[-]
20
[6]
20
[6]
20
[6]
240
[72]
600
[180]
ft
[m]
Setting Node Number, Baud Rate & Termination Resistor
NOTE: Units with hardware connection caps cannot accept
software-commanded address, baud rate or termination resistor
changes. These must be made using the switches in the connection
cap. Before commencing any changes, check for a connection cap.
It is secured to the rear of the encoder with 2 or 3 screws and due
to snug fit will require a strong pull to remove it after removing the
screws.
NOTE: Any changes to baud rate, node number, or resistor will not
take effect until the encoder is reset (typically power cycled).
Power-Up Sequence
The encoder will power-up in the pre-operational mode.
The message it will issue is:
ID: 0x07nn 0x00
nn=node number, typically:
0x01 for units with connection cap including hardware node and
baud rate selection. (software commands will not change node)
0x20 is the factory default for units with software-selectable
addressing. (software commands can change node number)
Setting Node Number:
To set the node number: write SDO object 0x3000 using command
0x22. The encoder internally adds 1 to the written value.
Example, encoder at node 20, change node address to 02:
ID: 0x620 0x22 0x00 0x30 0x00 0x01 0x00 0x00 0x00
Setting Baud Rate:
To set the baud rate: write the baud code to SDO object 0x3001.
Example, encoder at node 20, change baud rate to 125K = 0x03
ID: 0x620 0x22 0x01 0x30 0x00 0x03 0x00 0x00
Network
Baud
Rate
1M
500K
250K
125K
50K
20K
Baud
Code
07h
05h
04h
03h
01h
00h
To enable the termination resistor: write 01 to SDO object 3002h.
Ensure any devices on the bus power up at least 700mS after the
encoder with the termination resistor activated.
Saving Changes (Required):
To save baud rate/node/resistor changes, write 0x55 0xAA 0xAA
0x55 to SDO object 0x2300
Example, encoder at node 20, store changes
ID: 0x620 0x22 0x00 0x23 0x00 0x55 0xAA 0xAA 0x55
Cycle power after saving changes.
Measuring Position, Speed, and Acceleration
To read position and speed feedback into your device (Acceleration
measurement is not supported.): Following the instructions for your
master/scanner module for the CANOpen network, load the encoder
EDS file into your configuration. Assign it to the correct node
number. Store the configuration to the scanner module.
All of the position data and other parameters will be read by
the scanner module and placed in registers identified in the
configuration package.
Reading data without using the EDS file:
To read position: read SDO object 0x2000 (32 bit unsigned) or SDO
object 0x6004.
