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Reference Manual
00809-0100-4696, Rev AA
September 2004
Rosemount 848L
3-4
Capabilities Virtual Communication Relationship (VCRs)
There are a total of 20 VCRs. Two are permanent and 18 are fully
configurable by the host system. 25 link objects are available.
Host timer recommendations
T1 = 96000
T2 = 1920000
T3 = 480000
Block Execution times
Discrete Input = 40 ms
Discrete Output = 40 ms
Multiple Discrete Input = 40 ms
Multiple Discrete Output = 40 ms
RESOURCE BLOCK
FEATURES and
FEATURES_SEL
The parameters FEATURES and FEATURE_SEL determine optional
behavior of the Rosemount 848L.
FEATURES
The FEATURES parameter is read only and defines which features are
supported by the Rosemount 848L. Below is a list of the FEATURES the
Rosemount 848L supports.
UNICODE
All configurable string variables in the Rosemount 848L, except tag names,
are octet strings. Either ASCII or Unicode may be used. If the configuration
device is generating Unicode octet strings, you must set the Unicode option
bit.
REPORTS
The Rosemount 848L supports alert reports. The Reports option bit must be
set in the features bit string to use this feature. If it is not set, the host must
poll for alerts.
Network Parameter Value
Slot Time 8
Maximum Response Delay 4
Maximum Inactivity to Claim LAS Delay 60
Minimum Inter DLPDU Delay 7
Time Sync class 4 (1ms)
Maximum Scheduling Overhead 21
Per DLPDU PhL Overhead 4
Maximum Inter-channel Signal Skew 0
Required Number of Post-transmission-gap-ext Units 0
Required Number of Preamble-extension Units 1