CAN Control
© 2019 EMP, Inc.
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Status Message 2
Status Message 2 is a modern update to Motor Status Message 1 and is recommended for all new
applications/designs. The message supplies the same information as Motor Status Message 1 minus
Measured Percent Motor Speed, but adds:
Command Status
The source of command that is currently commanding the controller.
Service Indicator
Shows if the controller needs service.
Operation Status
Shows if the motor controller is running normal, derated, or not-operable.
Measured External Temperature
On R20C models equipped with external temperature capability, the external temperature measured value
will be available. The value will be either available in Status Message 2 or as an additional message if
using Motor Status Message 1.
SAE Messages
The R20C controller supports SAE defined messages for applications already using or comfortable with the SAE
J1939 protocol, and already own or willing to buy access to the SAE J1939 DA. See section 4.1 in
Component
Controller CAN Communication
, EMP document 9980001068, for detail on available SAE J1939 PGN pairs.
Dual Message Operation
The R20C supports an operating mode where both EMP messages and SAE messages are supported
simultaneously. The use case for this mode is primarily for a customer that is transitioning their system from
EMP Messages to SAE Messages and would prefer a single part number to satisfy both applications. Contact
EMP for more information.
CAN Baud Rate
At every startup (ignition enable on) R20C controllers automatically detect the CAN baud rate before transmitting
any data on the CAN bus. R20C supports 250K, 500K, and 1M baud rates. Automatic Baud rate detection is
enabled by default, but a fixed baud rate can be requested if required.
Measurement Tolerances
In the CAN status messages, when measured motor speed and measured motor power are reported, these are
calculated values. The resulting measurements are affected by circuit board component tolerances and therefore
are not to be used for diagnostics and may not be suitable for control system inputs.
This controller has the following tolerances on these measurements:
Speed:
± 2%
Power: ± 15%
Source Address
Factory Configured Addressing
The component communicates using a single address set in the factory calibration.
External Addressing (Optional)
The component communicates using a calibrated address assigned to an external resistance value. Component
calibrations may include up to 10 addresses.
