Festo CPX-CTEL-4-M12-5POL, Описание

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5 Diagnostics and error handling
48 Festo – P.BE-CPX-CTEL-EN – 1601b – English
After an interruption is determined, the relevant I-Port is queried cyclically and checked for a connec­
tion-capable device.
If a device is recognised, the following procedures are possible:
The recognised device corresponds to the I/O configuration presetting.
The system can continue to be operated without limitation.
If the I/O length of the recognised device is less than the length established in the config­
uration, the I/O bytes used are assigned to the “lower end” of the reserved address
space in the CPX system. The unassigned bytes at the “upper end” remain unused.
Example:
Configuration with an I/O length of 8 bytes. A device with an I/O length of 4 bytes is connected.
The 4 bytes of the device are assigned to the first 4 bytes in the address space of the I-Port.
The remaining 4 bytes remain unused.
I-Port Fixed I/O length 8 bytes Device: 4 bytes
I-Port Byte 0 Byte 0
Byte 1 Byte 1
Byte 2 Byte 2
Byte 3 Byte 3
Byte 4 X
Byte 5 X
Byte 6 X
Byte 7 X
Tab. 5.5
The recognised device has established a larger I/O length than in the I/O configuration presetting.
The system can still be operated. But the I/O bytes that “project” beyond the reserved address space
are ignored.
Example:
Configuration with an I/O length of 4 bytes. A device with an I/O length of 8 bytes is connected. The first
4 bytes of the device are assigned to the 4 bytes in the address space of the I-Port. The remaining
4 bytes of the device remain unused.
I-Port Fixed I/O length 4 bytes Device: 8 bytes
I-Port Byte 0 Byte 0
Byte 1 Byte 1
Byte 2 Byte 2
Byte 3 Byte 3
X Byte 4
X Byte 5
X Byte 6
X Byte 7
Tab. 5.6