5 Noncyclical data exchange
22
Declaration of a data structure in the "Single-ID" format
In the IO controller, you need to declare 1 data structure each (user-defined "STRUCT variable") for in-
coming and outgoing data exchange packets as the target and source memory for data exchange pack-
ets. Data exchange packets in the "Single-ID" format have a fixed length of 65 bytes and must be created
with the following structure:
Structure variable for data exchange packets in the "Single-ID" format
Data type Name Explanation
BYTE ID-PLC Sequential numbering for assigning the data exchange packets
from queries and responses
The "ID-PLC" value can be used by the IO controller for sequen-
tially numbering the outgoing data exchange packets. JUMO IO
devices enter the same number in the ID-PLC in the data ex-
change packet of the ensuing response, so that response and
query can be assigned at the IO controller, or so that an error in
the sequence of query and response can be intercepted by suit-
able control structures in the IO controller.
BYTE Outgoing:
DIR
Incoming:
ERROR
Data structure for outgoing data exchange packets:
„DIR“ ist die Data direction for transferring noncyclical data.
The data direction must be specified by the PLC programmer in
the data exchange packet of the query from the IO controller
and controls the processing of the data in the JUMO IO device
accordingly.
Coding:
Value = 1: Write (from IO controller to IO device)
Value = 2: Read (from IO device to IO controller)
Data structure for incoming data exchange packets:
In case of "ERROR", the JUMO IO device enters an integer val-
ue as error indicator. In the IO controller, "ERROR" can be eval-
uated via a corresponding control structure.
List of error values:
chapter 7 "Error messages", Page 57
WORD ID1 5-element ID of the data point from the noncyclical data table
(see chapter 5.2 "Data tables of noncyclical data", Page 36)
WORD ID2
WORD ID3
WORD ID4
WORD ID5
ARRAY[53 bytes]
(e.g. REAL, INT, BYTE)
VALUE Data point to be queried or overwritten of the noncyclical data
with a length of 53 bytes; however, only a maximum of 4 bytes
are currently used.
Value to be read/written of the data point; this variable can be
declared as any data type with a length of 4 bytes.
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