User Manual

IM 01C22T02-01E

A-24

APPENDIX 5. Link Master Functions

APPENDIX 5. LINK MASTER FUNCTIONS

A5.1 Link Active Scheduler

A link active scheduler (LAS) is a deterministic, centralized bus scheduler that can control communications on an H1

fieldbus segment. There is only one LAS on an H1 fieldbus segment.

An EJA supports the following LAS functions.

• PN transmission: Identifies a fieldbus device newly connected to the same fieldbus segment. PN is short for Probe

Node.

• PT transmission: Passes a token governing the right to transmit, to a fieldbus device on the same segment. PT is

short for Pass Token.

• CD transmission: Carry out a scheduled transmission to a fieldbus device on the same segment. CD is short for

Compel Data.

•Time synchronization: Periodically transmits the time data to all fieldbus devices on the segment and returns the

time data in response to a request from a device.

• Live list equalization: Sends the live list data to link masters on the same segment.

• LAS transfer: Transfers the right to be the LAS on the segment to another link master.

A5.2 Link Master

A link master (LM) is any device containing a link active scheduler. There must be at least one LM on a segment.

When the LAS on a segment has failed, another LM on the same segment starts working as the LAS.

Node address:

0x15

SlotTime = 5

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

There are 3 LMs on this segment.

FA0501.EPS

Figure 1. Example of Fieldbus configuration-3 LMs on Same Segment