DeviceNet Glossary
Bandwidth:
CANbus:
Configuration:
Determinism:
Frame Rate:
MACID:
DeviceNet, like other serial networks,
supports a certain number of bits per second sent on the
wire. The actual network traffic is reported as a
percentage of the theoretical maximum, and is called %
Bandwidth. NetMeter's measurements include bandwidth
lost due to bus errors and retries but most other
diagnostic tools only include
messages in
bandwidth calculations.
DeviceNet is based on a low-level network
standard known as CAN or CANbus. Other networks
that use CAN include CANOpen and SDS. Although
these networks are based on CAN, physical layer and
upper layer protocol differences limit the use of the
NetMeter with these networks.
Because DeviceNet networks allow you
to use devices in many different ways, each device must
be configured before it will work properly on a DeviceNet
network. For some devices, this is as simple as setting a
switch to select the MACID (node address) and baud
rate. Other devices require configuration from a PC-
based software tool (Available from SST). Most
importantly, configuration means that before you replace
a device with another, identical device, you must
configure the replacement device properly.
Determinism is a measure of the
predictability of the performance of a system (including
but not limited to networks). Communication errors and
delays caused by high bandwidth utilization reduce
determinism, making the system less predictable in its
operation (less deterministic).
DeviceNet messages are sent in one or
more CAN message structures called Frames. Frame
Rate is the number of these structures sent in 1 second.
Since one DeviceNet message may require several CAN
frames, the frame rate is not necessarily the same as the
message rate.
Each device on a DeviceNet network has a
unique "Address", a number between 0 and 63. This
Address is known as the MACID or Node number.
successful
CANH
/CANL
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