Emergency Object

In order to be able to inform other participating devices on the CANopen bus about internal device errors or CAN bus errors, CANopen Bus Couplers can make use of the emergency object. It has a high priority, and provides valuable information about the state of the device and of the network.

Note
Warning It is strongly recommended that emergency objects are evaluated - they provide a valuable source of information.

Structure of the emergency message

The emergency object is always 8 bytes long; it contains first the 2-byte error code, then the 1-byte error register, and finally the additional code of 5 bytes. This is divided into a 2-byte bit field and a 3-byte parameter field:

11 bit identifier	8 bytes of user data
0x80 (=128dec) + node-ID	EC0	EC1	EReg	Bit field 0: Comm	Bit field 1: DevErr	EMCY Trigger	Info 0	Info 1

Key

Parameters	Explanation
EC0	Error Code Low-Byte. Not used (always zero)
EC1	Error Code High-Byte. 0x50 = device error, 0x81 = communication error, 0x00 = error reset
EReg	Error register. 0x81 = device error, 0x91 = communication error
Bit field 0: Comm	Bit field communication error:
	0x01	Guarding delayed or failed
	0x02	Sync delayed or failed
	0x04	Incorrect PDO length parameterized
	0x08	Event timer timeout: RxPDO not received in time
	0x10	Receive queue overrun
	0x20	Transmit queue overrun
	0x40	CAN bus OFF
	0x80	CAN warning limit exceeded
Bit field 1: DevErr	Bit field device error:
	0x01	Terminal error
	0x02	K-Bus error / IP-Link error
	0x03	-
	0x04	EEPROM error
	0x10	Unsupported terminal plugged in (BK5110, LC5100)
	0x80	Altered HW configuration.
EMCY trigger	The emergency trigger byte contains the code for the particular error that has triggered the emergency telegram. If an error has been rectified, an emergency telegram with the error code 0x0000 is sent, and the emergency trigger contains the description of the error that has been corrected. Errors that are still current are signaled here in the bit fields. Once the Bus Coupler is free of errors, it sends an emergency telegram containing zeros everywhere other than in the emergency trigger.
	0x01	CAN warning limit exceeded (too many error frames)
	0x02	CAN bus OFF state has been reached. Since the coupler can no longer send an emergency telegram, an emergency telegram with trigger 0x40 is sent when the bus leaves the "off" state (a new CAN controller initialization).
	0x03	Transmit queue overrun: CAN messages are being lost
	0x04	Transmit queue overrun: CAN messages are being lost
	0x06	Incorrect PDO length parameterized (check mapping). Info 0: parameterized (expected ) PDO length in bytes Info 1: current PDO length (results from the added lengths of the mapped objects)
	0x07	Sync delayed (time-out after communication cycle period, index 0x1006) or failed
	0x08	Guarding or heartbeat delayed (timeout following guard time x lifetime factor, or following consumer heartbeat time) or failed.
	0x09	Altered HW configuration. The inserted terminals or the composition of the extension modules has been changed since the last save.
	0x0A	Event timer timeout: RxPDO not received in time
	0x0B	Logical Tx queue overrun: SYNC interval too short. The coupler could not deliver all the TxPDOs before the following SYNC telegram. The TxPDOs are then, for instance, delivered in every second SYNC interval. Remedy: Lengthen the SYNC interval or raise the transmission type. In some cases it may be appropriate to reduce the I/O count at this bus station (e.g. by moving I/Os to the neighboring station)
	0x0C	Unsupported terminal plugged in (BK5110 or LC5100) Info 1: terminal number (1...64)
	0x0E	EEPROM error; an error occurred when saving the configuration in the EEPROM
	0x0F	K-Bus error Info 0: Error type: 0x03: command error (no terminal number), 0x04: Interruption in the K-Bus or in IP-Link 0x05: Error in register communication 0x0B: Timeout in extension box 0x0C: More than 120 modules in the IP-Link ring 0x0D: K-Bus command error, or IP-Link: Unknown extension box 0x0E: Alignment error 0x0F: Number of terminals changed 0x10: K-Bus reset: Bit length of K-Bus changed 0x11: K-Bus reset: Number of terminals changed 0x12: K-Bus reset: Type of a terminal changed Info 1: terminal number (1...64)
	0x10	Terminal error Info 0: terminal number (1...64) Info 1: general diagnostic status code for the terminal: Bit 0,1: Channel number (00: channel 1; 01: channel 2; 10: channel 3; 11: channel 4) Bit 2...6: reserved Bit 7: Error (=1: occurred; =0: corrected). See the status register of the terminal or of the extension module for more detailed information about the type of error.
Info 0, Info 1	Contains additional error information; its meaning depends on the emergency trigger (see above)

Example of emergency behaviour

1.: The CAN error counter in a Bus Coupler has exceeded the warning limit (too many error frames). It sends an emergency telegram with the identifier 0x80 + node address (default setting) with the following contents:
00 81 91 80 00 01 00 00
The first three bytes (0x00 81 91) identify a communication error, while the bit field 0 (0x80) indicates that the CAN Warning Limit has been exceeded. The EMCY trigger (0x01) shows that the emergency was triggered as a result of exceeding the warning limit.

2.: Immediately afterwards a cable goes open circuit on the second channel of the 4-20 mA analog input terminal plugged into the tenth location. The Bus Coupler sends another emergency telegram with the following contents:
00 50 91 80 01 10 0A 82
The first two bytes (0x00 50) identify a hardware error. Bits 0 (generic error), 4 (communication) and 7 (manufacturer-specific) are set in the error register (0x91). Bit 7 is set in bit field 0 (0x80), showing that the CAN warning limit continues to be exceeded. Bit 0 is set in bit field 1 (0x01), indicating a terminal error. The EMCY trigger (0x10) indicates that it is this terminal error that has triggered the emergency telegram. Finally, Info 0 (0x0A) indicates the terminal number (10) while Info 1 (0x82) shows in bit 1 and bit 7 that channel 2 has an error.

3.: If the error counter now falls below the warning limit again, the coupler sends the following emergency telegram:
00 00 81 00 01 01 0A 82
The error code (00 00) in the first two bytes shows that an error has been reset. The error register (0x81) continues to show the device error, because the cable is still broken. Bit field 0 (0x00) shows that the communication error is no longer present. According to bit field 1 (0x01) the terminal error continues to be present. The EMCY trigger (0x01) indicates that the reason for the transmission was the resetting of the CAN warning limit. Info 0 and Info 1 continue to show the terminal's diagnostics status code.

4.: Once the broken cable has been repaired this error is also reset, and the coupler sends the following emergency telegram:
00 00 00 00 00 00 00 00