Network Force/Torque Sensor System

Net F/T Installation and Operation Manual
Document: 9620-05-net ft-11
15. CAN Bus Operation
Message
to Net F/T
Request
Long Data
15.1 Overview
The Net F/T supports a basic CAN protocol to allow reading of force/torque data and system status word
over CAN without the need for a DeviceNet scanner.
The CAN Bus base address and Baud Rate settings are configured using the DIP switches. Refer to
Section 3.10—DIP Switches and Termination Resistor for additional information.
To use the Net F/T’s CAN bus protocol, CAN Bus must be selected on the Communications page and
power must be present on the Pwr/CAN connector.
15.2 Protocol Description
A request data message sent to the Net F/T initiates copying of the current set of force and torque data
into an output buffer and the subsequent transmission of the output buffer.
Depending on the request message identifier (REQUEST LONG or REQUEST SHORT), the Net F/T
either sends 32-bit values packed into four messages or 16-bit values packed into two messages.
Values are in little endian format (least-significant byte first). For example, a 16-bit value received as
0x56 0x02 represents 0x0256. Signed numbers use 2’s complement format. The 32-bit value received as
0x0F 0xCF 0xDA 0xDA 0xFD represents 0xFDDACF0F, which is a negative number (because the
highest bit is set). Its decimal value is -35991793.
If a data request message is received during an ongoing transmission, the ongoing transmission will be
terminated and the new request processed.
15.3 Base Address and Communication Format
The CAN Bus base address is set by DIP switches 1 through 6. For more information refer to Section
3.10.2—Node Address and Table 3.1—CAN Bus Base Address Switch Settings. The factory set base
address is 432.
Response
from Net
F/T
Fx and Tx
data
Fy and Ty
data
Fz and Tz
data
Status and
sample
number
CAN
Identifier
Base
Address
Base
Address
+1
Base
Address
+2
Base
Address
+3
Base
Address
+4
Table 15.1—Request Long Data
Data
length in 1 st –4 th data bytes 5 th –8 th data bytes Comment
bytes
1 0x01 (BYTE) N/A Sends a copy of force and torque
data in long format (an ongoing
transmission will be terminated)
8 Fx value (DINT) Tx value (DINT) X-axis force and torque values in
long format
8 Fy value (DINT) Ty value (DINT) Y-axis force and torque values in
long format.
8 Fz value (DINT) Tz value (DINT) Z-axis force and torque values in
long format.
8 system status
(DINT)
sample number
(DINT)
System status word and sample
number in long format.
Pinnacle Park • 1031 Goodworth Drive • Apex, NC 27539 USA • Tel: +1.919.772.0115 • Fax: +1.919.772.8259 • www.ati-ia.com • Email: info@ati-ia.com
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