Curtis 1353 - Emergency and Heartbeat Messages; Emergency Message Format; Heartbeat Message Functionality

3 — CANOPEN COMMUNICATIONS
pg. 19
Return to TOC Curtis 1353 CANopen Expansion Module Manual – June 2017
EMERGENCY MESSAGES
Emergency messages are the second highest priority in CANopen and the highest priority that a
slave (like the 1353) can transmit. ese messages are sent sporadically whenever there is a change
of state in the 1353’s fault ags.
To prevent fast-changing fault bits from ooding the bus, a minimum Emergency Rate between
messages can be programmed by Curtis programmer or SDO.
An Emergency Message consists of 8 data bytes.
Data bytes 1 and 2 dene the error category.
Data byte 3 is the CANopen-required error register. Curtis products dene this as 0x01 if there is a
fault present and 0x00 when this fault is clear.
Data bytes 4 through 8 dene the specic fault. e 1353 will place the current 24-bit hour meter
into data bytes 4 through 6.
Bytes 7 and 8 are not used by the 1353 and are always 0x0000.
e emergency message format indicating an error is shown below.
byte 1 byte 8
Error Code Hour Meter
0x01 0x0016-bit field 0x0000
Curtis
Code
0xFF
HEARTBEAT
e heartbeat message is a very low priority message, periodically sent by each slave device on the
bus. e heartbeat message has a single byte of data and requires no response. Once the 1353 is in
the Pre-Operational state, the next heartbeat will be issued and will continue until communication
is stopped.
e heartbeat message has only one data byte. e top bit is reserved and should be set to zero. e
bottom 7 bits hold the current NMT device state.