Copley Controls Xenus R10 Manual page 168

Accelnet R21
CABLING FOR COMMUNICATIONS
MULTI-DROP RS-232
The RS-232 specification does not support multi-drop (multiple device) connections as does RS-485 or CAN. However, it is possible to address multiple
CAN-enabled Copley drives from a single RS-232 port. First, an RS-232 connection is made between the computer and drive #1 which must be given a CAN
address of 0. Under normal CAN operation, this address is not allowed for CAN nodes. But, in this case, drive #1 will act as a CAN master and so address
0 is allowed. Next, CAN connections are made between drive #1, drive #2, and so on in daisy-chain fashion to the last drive. The last drive in the chain
must have the 120 W resistor between the CAN_H and CAN_L signals to act as a line-terminator. Finally, the CAN addresses of the drives downstream from
drive #1 are set to unique numbers, none of which can be 0.
When ASCII data is exchanged over the serial port, the commands are now preceded with the node address of the drive. Drive #1 converts the data into
CAN data which is then sent to all of the drives in the chain. It now appears as though all drives in the chain are connected to the single RS-232 port in
the computer and for that reason we refer it as multi-drop RS-232.
CANopen Data
R21-NC-10
R21-NC-01
R21-NC-10
R21-NC-01
Copley Controls, 20 Dan Road, Canton, MA 02021, USA
Tech Support: E-mail: sales@copleycontrols.com, Internet: http://www.copleycontrols.com
R21-NT
RUGGEDIZED DIGITAL
BRUSHLESS/BRUSH MOTORS
R21-SK
Sub-D 9F
Drive #1
CAN Master
CAN Address = 0
(Required)
RS-232 Multi-drop Rules:
The drive with the RS-232 connection becomes a
CAN bus master that sends serial commands
down-stream to other drives.
Downstream node-ID range is 0x01~0x7F (1~127)
All downstream node-ID's must be unique
Drive #2
CAN Node
CAN Address = 1
(Optional)
Drive #3
CAN Node
CAN Address = 2
(Optional)
Tel: 781-828-8090
R21
SERVO DRIVE FOR
Serial Data
ASCII or Binary
format
The node-IDs shown here are for
example and can be any number
that follows the RS-232 Multi-drop
rules (see box above).
Fax: 781-828-6547
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