Yokogawa EJX930A - Manual (Page 130)

A6-2
IM 01C25T02-01E
A6.3 Transfer of LAS
There are two procedures for an LM to become the LAS:
• If the LM whose value of [V(ST)×V(TN)] is the smallest on a segment, with the exception of the current
LAS, judges that there is no LAS on the segment, in such a case as when the segment has started up or
when the current LAS has failed, the LM declares itself as the LAS, then becomes the LAS. (With this
procedure, an LM backs up the LAS as shown in the following figure.)
• The LM whose value of [V(ST)×V(TN)] is the smallest on a segment, with the exception of the current LAS,
requests the LAS on the same segment to transfer the right of being the LAS, then becomes the LAS.
LM
Node address:
0x15
SlotTime = 5
LM
Node address:
0x16
SlotTime = 5
Node address: 0x14
SlotTime = 5
Basic device
Node address:
0xF1
Basic device
Node address:
0xF2
Basic device
Node address:
0xF3
Basic device
Node address:
0xF4
LAS
LAS
In the event that the current LAS in
this segment (node address 0x14)
fails, the LM with the address of 0x15
takes its place to become the LAS.
LM
FA0602.ai
Figure A6.2 Backup of LAS
To set up the transmitter as a device that is capable of backing up the LAS, follow the procedure below.
NOTE: When changing the settings in the transmitter, add the transmitter to the segment in which an LAS
is running. After making changes to the settings, do not turn off the power to the transmitter for at least 30
seconds.
(1) Set the node address of the transmitter. In general, use an address from 0x10 to [V(FUN) - 1].
Not used
LM device
Not used
Basic device
Default address
Portable-device address
V (FUN)
V (FUN) + V (NUN)
V (NUN)
0xFF
0xFC
0xFB
0xF8
0xF7
0x00
FA0603.ai
0x0F
0x10
0x13
0x14
Bridge device
Figure A6.3 Node Address Ranges