22.2 CPWRIT (CAN-PDO write function)
Function CPWRITE is used for write access to instrument PDOs. Because of the normal quantity of min. 2 PDOs per in
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struments, the data quantity of 2 PDOs 2 with 2 COB-IDs was grouped in a block.
Node address and COB-ID (CAN-OBject IDentifier) parameter setting is in the block. Moreover, node guarding for moni
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toring the CAN communication to the specified node can be switched on.
Data sent to the instrument must be interpreted according to instrument specification. Groups of 4 transmitted bytes
represent different data types.
To provide the bytes according to the required data type, a conversion function for transforming the value in the engi-
neering into 1 to 4 bytes is available (see function AOCTET).
Examples: R1+R2 > Int16 / R1+R2+R3+R4 >Long
a
Important note: The heart beat protocol is not supported. If an instrument can be operated only via “heart beat”,
the guarding function must be switched off.
Digital inputs:
start The function is active, unless the input is connected, or if start=1 is connected.
Digital outputs:
et-err 0 = no engineering error
1 = no CAN-HW (KS98 type)
multiple node monitoring
id-err 0 = correct node id
1 = faulty node id or the instrument does not reply
own node ID was specified as “NodeId”
no free send PDOs (TPDO)
valid bit follows the node status with the node guarding active
(0=”preoperational”, 1=”operational”) always 1 with the node guarding switched off
Analog outputs:
T1 1 ...T1 8 1st to 8th output value in byte format (8-bit) for COB-ID 1
T2 1 ...T2 8 1st to 8th analog output value in byte format (8-bit) for COB-ID 2
Configuration parameters (can be changed only during OFFLINE):
NodeId CAN node address
Guard node guarding off/on
COBID1 decimal ID of the first CAN object identifier
COBID2 decimal ID of the second CAN object identifier
Description of KS98 CAN bus extension 9499 040 50611
CPWRIT (CAN-PDO write function) 142
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