Fluid Components International ST100 Series Foundation Fieldbus - Manual (Page 23)

ST100 Series Foundation Fieldbus
Fluid Components International LLC 21
INDEX PARAMETER DATA TYPE (LENGTH) INITIAL VALUE DESCRIPTION
38 TRK_IN_D DS-66 BNcO BncO=Bad-Not connected/ off
39 TRK_VAL DS-65 BNc BNc = Bad_Not connected /0.0
40 FF_VAL DS-65 BNc BNc = Bad_Not connected /0.0
41 FF_SCALE DS-68 0-100%
42 FF_GAIN Float 0.0
43 UPDATE_EVT DS-73
44 BLOCK_ALM DS-72
45 ALARM_SUM DS-74 All alarms enabled
46 ACK_OPTION Bitstring(2) Auto ack disabled
47 ALARM_HYS Float 0.5%
48 HI_HI_PRI Unsigned8 0
49 HI_HI_LIM Float +INF
50 HI_PRI Unsigned8 0
51 HI_LIM Float +INF
52 LO_PRI Unsigned8 0
53 LO_LIM Float -INF
54 LO_LO_PRI Unsigned8 0
55 LO_LO_LIM Float -INF
56 DV_HI_PRI Unsigned8 0
57 DV_HI_LIM Float +INF
58 DV_LO_PRI Unsigned8 0
59 DV_LO_LIM Float -INF
60 HI_HI_ALM DS-71
61 HI_ALM DS-71
62 LO_ALM DS-71
63 LO_LO_ALM DS-71
64 DV_HI_ALM DS-71
65 DV_LO_ALM DS-71
Link Master Function
The ST100 with Foundation Fieldbus protocol supports the Link Master function, and it is capable of becoming a Link Active Scheduler (LAS).
A Link Master (LM) is any device containing Link Active Scheduler (LAS) functionality that can control communications on an H1 Fieldbus Link. There
must be at least one LM on an H1 Link; one of those LM devices will be elected to serve as LAS.
A Link Active Scheduler (LAS) is a deterministic, centralized bus scheduler that maintains a list of transmission times for all data buffers in all de-
vices that need to be cyclically transmitted. Only one Link Master (LM) device on an H1 fieldbus Link can be functioning as that link’s LAS.
Operation
The Link Active Scheduler (LAS) has a list of transmit times for all data buffers in all devices that need to be cyclically transmitted.
When it is time for a device to send a buffer, the LAS issues a Compel Data (CD) message to the device.
Upon receipt of the CD, the device broadcasts or “publishes” the data in the buffer to all devices on the fieldbus. Any device configured to
receive the data is called a “subscriber”.
Scheduled data transfers are typically used for the regular, cyclic transfer of control loop data between devices on the fieldbus.