Error handling and diagnostics
EL6751
167
Version: 3.5
Fig. 137: TwinCAT tree: Diagnostic variables of the EL6751
Error
Shows the number of slaves whose Box State is not equal to zero. Only check the BoxState of the slaves if
this value is other than 0.
CANState
Bit 0: CAN controller is in BUS OFF state; due to an excessive number of CAN errors (error frames) the CAN
controller no longer takes part in the bus traffic; in this case there is a serious physical error in the CAN
network (e.g. insufficient or too many termination resistors, at least one device with invalid baud rate, short
circuit, etc.). The Bus Off state can only be quit with a CAN node reset.
Bit 1: CAN controller warning limit reached; the send or receive error counter of the CAN controller has
exceeded 96.
Bit 2: Rx queue overrun; overflow of the internal receive buffer. Data retrieval by the controller is too slow.
Bit 3: Hi-Prio Tx queue overrun; transmit buffer overflow for PDOs and SYNC messages.
Bit 4: Lo-Prio Tx queue overrun; transmit buffer overflow for SDOs, guarding, heartbeat, etc.
Bit 5: CAN transmission error; this bit is set when no data can be transmitted, e.g. if the EL6751 connector is
unplugged.
Bit 7: internal Rx queue full; the data are not read in via the CAN interface (function available from firmware
9).
Bit 15: toggles when the CAN-SYNC message is sent. This enables the function of the CAN multiplier (CAN
transmission in every n
th
EtherCAT cycle) to be checked.
RxErrorCounter
Faulty receive data; this is set to a certain value in the event of an error and decremented to one once
faultless communication has resumed.
TxErrorCounter
Faulty transmission data; this is set to a certain value in the event of an error and decremented to one once
faultless communication has resumed.
DiagFlag
: Shows whether the diagnostics information on the card has changed. This can be read off using
ADS-Read. For that purpose, specify the net ID of the EL6751, the port number 200 and the IndexGroup
0xF100. The IndexOffset and the length then relate to the diagnostic data. (Note: The Box States are also
available as box variables.)
Offset 1-127: BusStatus List, 1-127 one byte each station address which contains the station status (see
BoxState for CANopen boxes)
