User Manual
IM 01C22T02-01E
A-26
APPENDIX 5. Link Master Functions
A5.4 LM Functions
No. Function Description
LM initialization
Startup of other 
nodes (PN and 
Node Activation 
SPDU 
transmissions)
PT transmission 
(including final bit 
monitoring)
CD transmission
Time synchronization
Domain download 
server
Live list equalization
LAS transfer
Reading/writing of 
NMIB for LM
Round Trip Delay 
Reply (RR)
Reply to DLPDU
Long address
1
2
3
4
 5
6
7
8
9
10
11
TA0504.EPS
When a fieldbus segment starts, 
the LM with the smallest [V(ST) × 
V(TN)] value within the segment 
becomes the LAS. 
At all times, each LM is checking 
whether or not a carrier is on the 
segment. 
Transmits a PN (Probe Node) 
message, and Node Activation 
SPDU message to devices which 
return a new PR (Probe Response) 
message. 
Passes a PT (Pass Token) 
message to devices included in the 
live list sequentially, and monitors 
the RT (Return Token) and final bit 
returned in reply to the PT. 
Transmits a CD (Compel Data) 
message at the scheduled times. 
Supports periodic TD (Time 
Distribution) transmissions and 
transmissions of a reply to a CT 
(Compel Time).  
Sets the schedule data. 
The schedule data can be 
equalized only when the Domain 
Download command is carried out 
from outside the LM in question. 
(The version of the schedule is 
usually monitored, but no action 
takes place, even when it changes.)
Transmits SPDU messages to LMs 
to equalize live lists. 
Transfers the right of being the LAS 
to another LM. 
See Section A5.5. 
Not yet supported in the current 
version. 
Not yet supported in the current 
version. 










