ProSoft Technology PS-QS-1x10-0781 - Manual (Page 22)

FieldServer Configuration Manual Page 22 of 90
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If the two poll blocks fall within these two address spans, the poll will be successful, however, if all
50 registers are polled in a single poll it will fail
Configuration 2: Map Descriptor 1 serves up 40001 Length 50
For this to work, all 50 points must be contiguous in the same Data Array so that one Map
Descriptor can be created. If all 50 registers are polled in a single poll it will be successful. If the
Client polling algorithm keeps a fixed length of 50, and then decides to poll address 40050, length
50, the poll will fail because addresses 40051 through 40099 are not declared in the FieldServer.
Configuration 3. Map Descriptor 1 serves up 40001 Length 200
For this to work, points must be contiguous in the Data Array, and the Data Array length must be
at least 200. Since Modbus can poll a maximum length of 125, a Client cannot poll the required
registers and encounter an address that is not configured. This is therefore the most robust
solution, and only costs a few points.
5.1.1.3 Special Application: Separating Responsible Map Descriptors
Responsible Map Descriptors are active Map Descriptors that control the Communications (see section 4). Two
Responsible Map Descriptors cannot share the same Data Array Offset due to monitoring functions present in the
kernel (Refer to Section 4.3 for more information). If two Responsible Map Descriptors require access to the same
data, the data can be made accessible to the second Responsible Map Descriptor by moving it to a second Data
Array.
5.1.1.4 Special Application: Creating a LonWorks SNVT_Switch from 2 Modbus registers.
Float Data Array
With data from
Modbus address 40200
Bit Data Array
With data from
Modbus address 11235
Server Side Data
Array
-------------------------
Offset 20: Value
-------------------------
Offset 21: State
-----------
-----------
---
SNVT_STATE
State Value
40200 11235
LonWorks Server Map
Descriptor
Data Array 1
a
t
a
A
r
r
a
y
1
Data Array 2
Rdbc Wrbx
Move
Server 1 Server 2