Campbell Scientific SDM-CAN Datalogger to CANbus Interface - Manual (Page 10)

SDM-CAN Datalogger-to-CANbus Interface
By this process the SDM-CAN can capture data on the CAN-Bus and filter out
packets of interest to the user. Within each data packet the device is able to
read one or more data values and convert them to numeric values compatible
with the normal data stored by the datalogger.
The SDM-CAN will act as a passive listen-only device with its transmitter
disabled in hardware. Alternatively it can be configured to send/respond to
Remote Frame Requests, allowing it to poll remote devices for data. Data
packets can also be constructed to allow it to send data out onto the CAN-Bus
so it then acts as a sensor itself.
Data is transferred between the SDM-CAN interface and the datalogger using
Campbell Scientific’s high speed SDM communications protocol. This
protocol allows the SDM-CAN to be used in parallel with other SDM devices
(including other SDM-CAN interfaces) which might, for instance, be on other
CAN-Bus networks in the same vehicle.
In addition to connectors to the CAN network and the datalogger, an RS232
port is also provided both for diagnostics and operating system upgrades.
1.2 Specifications
1.2.1 General Features and Specifications
• Uses Campbell Scientific’s SDM communication protocol to communicate
with the datalogger via a three wire serial multidrop connection. Support
is planned for CR10X, CR23X, CR7, CR5000 and CR9000 dataloggers.
• Up to 16 units can be used per datalogger, with the modules’ SDM address
set by rotary switch.
• CAN 2.0A and 2.0B active and passive modes supported
• Up to 1Mbaud max data rate. Standard baud rates supported are 1M,
800K, 500K, 250K, 125K, 50K, 20K and lower. Other non-standard baud
rates may be possible – please contact Campbell Scientific.
• Receive and transmit up to 128 different data values from up to 128 CAN
ID’s.
• Build and send a CAN data frame.
• Send Remote Frame Requests.
• Send data frame in response to an external Remote Frame Request.
• Supports a number of power down modes to allow power saving in power
critical applications.
• All configuration of the interface is specified within the user’s datalogger
program.
• LED status flash at power up
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