Yokogawa digitalYEWFLO (DY-FF) - Manual (Page 119)

A7-2
IM 01F06F00-01EN
A7.3 Transfer of LAS
There are two procedures for an LM to become the LAS:
(1) 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 fi gure.)
(2) 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
FA0702.ai
Figure A7.2 Backup of LAS
To set up a digitalYEWFLO as a device that
is capable of backing up the LAS, follow the
procedure below.
NOTE: When changing the settings in a
digitalYEWFLO, add the digitalYEWFLO to the
segment in which an LAS is running. After making
changes to the settings, do not turn off the power to
the digitalYEWFLO for at least 60 seconds.
(1) Set the node address of the digitalYEWFLO.
In general, use an address from 0x14 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
FA0703.ai
0x0F
0x10
0x13
0x14
Bridge device
Figure A7.3 Node Address Ranges
(2) In the LAS settings of the digitalYEWFLO,
set the values of V(ST), V(MRD), and V(MID)
to the same as the respective lowest
capability values in all the devices within
the segment. An example is shown below.
DlmeBasicInfo (digitalYEWFLO Index 361 (SM))
Sub-
index
Element
digital
YEWFLO
Device
1
Device
2
Device
3
Description
1 Slot Time 4 8 10 20
Capability
value for V(ST)
3
MaxResponse
Delay
3 6 3 5
Capability
value for
V(MRD)
6
MinInterPdu
Delay
4 8 12 10
Capability
value for
V(MID)
In this case, set SlotTime, MaxResponseTime, and
MinInterPduDelay as follows:
Confi guredLinkSettingsRecord
(digitalYEWFLO Index 369 (SM))
Subindex Element
Setting
(Default)
Description
1 SlotTime 20 (4095) V (ST)
3 MaxResponseDelay 6 (5) V (MRD)
6 MinInterPduDelay 12 (12) V (MID)