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FX
-J1939 User's Manual
3U
Bit
OFF:
Bit 4
ON:
Bit 5, 6
Not used
Bit 7
Module initialization state
Bit 8 to 15
Not used
*1.
If the arbitrary address capability is activated (BFM #25 bit 2 = ON) and the address set in BFM #27/
#28 is in the "dynamic" address range, the FX
network for a node address. If an address conflict occurs, the FX
address and set BFM #29 bit 9 to ON.
If the module is set to single address capable (arbitrary address capability is de-activated), an address
conflict will cause the FX
the bus.
The status of this bit is stored to Flash ROM.
*2.
There are two events that might cause the FX
address:
-
The reception of a "commanded address" message
-
A node with higher priority claims the address currently used by the FX
In such a case, bit 3 is set to ON when a new a node address is claimed successfully by the FX
J1939. If no new node address could be claimed, BFM #29 bit 1 is set to ON.
*3.
This bit must be set to ON to start data exchange with other network nodes. The configuration of the
module can only be changed while this bit is OFF.
Note
If a configuration BFM was changed during online mode, BFM #29 bit 5 is set ON.
*4.
While this flag is ON, the FX
Note
• During this time, do not write (TO instruction, etc) to any BFMs.
If write access is performed, FX
• During this time, do not read (FROM instruction, etc) any BFMs other than BFM #25, as the current
values of the BFM might change during initialization.
5.8
[BFM #26] FROM/TO Watchdog
The FROM/TO Watchdog can be used to monitor if the PLC program cyclically accesses data BFMs #100 to
#399 or the extended data area in BFM #1300 to #1799.
After the first FROM/TO on the data BFM, the Watchdog will check if the next access to the data BFMs takes
place before the time set in BFM #26 expires.
BFM #26 sets the Watchdog timer in units of 10 ms [default value: K20 (200 ms)].
Note
• Any new valid value written to BFM #21, #24, #25 bit 2, #26 or #27 is automatically stored to flash ROM.
The maximum number of writes to the built-in flash ROM is 10,000 times.
Therefore, when creating a program, do not frequently write to such buffer memories.
• If the watchdog expires, bit 7 in BFM #29 is set to ON, and the "PLC RUN>STOP messages" defined in
BFM #1900 to #1927 are transmitted on the network.
• The FROM/TO watchdog can be restarted by writing the setting value to BFM #26 again, which will also
reset the error flag in BFM #29.
• If the watchdog function is not required, it can be deactivated by writing K0 to BFM #26.
38
FROM (Read Access)
Request configuration mode
*3
Request online mode
*4
-J1939 to send a "can not claim" message and stop exchanging data with
3U
For details on the node address, refer to Section 5.9 and Section 5.10
-J1939 is initializing.
3U
3U
Access
TO (Write Access)
Not used
-J1939 will start to negotiate with other nodes in the
3U
For error status (BFM #29), refer to Section 12.2
-J1939 to lose permission to use its current node
3U
-J1939 will cause an error in BFM #29 bit 5.
5 Allocation of Buffer Memories
5.8 [BFM #26] FROM/TO Watchdog
-J1939 will attempt to claim a new
3U
-J1939
3U
-
3U
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