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Chapter
6
Operating Instructions
Flexi Soft Gateways
142
© SICK AG • Industrial Safety Systems • Germany • All rights reserved
8012664/XB29/2013-06-11
Subject to change without notice
Fieldbus gateways
6.2.7
Node guarding
An NMT master (e.g. a PLC with integrated CANopen master) uses the NMT error control
object to detect a failure of an NMT slave with the address N. The NMT slave must reply
within the node guarding time to the request from the NMT master. The node guarding
time must be monitored by the NMT master.
The NMT master sends a CAN message with identifier <700h + node ID> and RTR bit
(remote transmission request).
NMT master request:
CAN ID
RTR
DLC
DATA
700h + N
1
0
The slave (e.g. the FX0-GCAN) then sends a status byte Byte1 with the following content:
Slave response:
CAN ID
DLC
DATA
700h + N
1
Byte1
Bit
Meaning
7
Toggle bit, changes value between two sequential requests
6 … 0
NMT status
4 = Stopped
5 = Operational
127 = Pre-operational
Bootup
On bootup, the gateway sends a bootup message with the CAN ID 700h+N, DLC = 1 and
Byte 1 = 0.
Heartbeat producer
If the gateway is configured as heartbeat producer (i.e. if SDO 1017 contains a value for
the producer heartbeat time, see Tab. 119 “Supported SDOs” on page 146), it sends a
cyclic message with the CAN ID 700h+N, DLC = 1 and Byte 1 = 05h. The toggle bit (Bit 7)
is always 0.
Heartbeat consumer
If the gateway is configured as heartbeat consumer (i.e. if SDO 1016.1 contains a value for
the consumer heartbeat time, see Tab. 119 “Supported SDOs” on page 146), at least one
node guarding message must be received within the configured consumer heartbeat time
(typically from an NMT master).
Tab. 107: Request from NMT
master
Tab. 108: Response from
slave
Tab. 109: Remote transmis-
sion request