User manual

IEC61131 User and Reference Manual
April 22, 2008
243
dlogread
Data Logger Extract Function Block
Description
The dlogread function block reads a single record in the data log identified by LogID.
Each record in the data log is assigned a sequence number to identify the record. The
dlogread function block and the SCADALog application use this sequence number to
identify records in the data log. The number of data fields in a record and the data types of
the fields are defined using the dlogcnfg function block.
The dlogread function block pulls data from the log as Real type variables. The data 1 to
data 8 outputs may only be connected to real variables. If a field data type is ISaGRAF
boolean, ISaGRAF integer, or ISaGRAF timer, the output of dlogread must be converted to
this type before connecting to the output variable. See the example below.
enable
readRecord
logID
error
status
dlogread
seqNum
data1
data2
data3
data4
data5
data6
seqNo
data7
data8
hundredthSeconds
Arguments
Inputs
Type
Description
enable
Boolean
When t he enable input changes FALSE to
TRUE, the error and status outputs are updated.
See the Status Code table below.
readRecord
Boolean
When enable is set to TRUE, readRecord
changes from FALSE to TRUE, data for the
requested sequence number is read. The error and
status outputs are also updated. See the Status
Code table below.
logID
Integer
Identifies the internal log (1 to 16).
seqNo
Integer
The sequence number of the record to be read.
Note that the seqNo is signed 32-bit integer, it will
start from 0, increase to 2147483647 (maximum
sign 32-bit integer), then roll over to –2415919103
(minimum sign 32-bit integer), and then increase
back to 0. This cycle is continuously repeated.