315-4PN33

n Any data transferred from the periphery must be preceded by a
Start followed by the data characters and the end character.
Depending of the byte width the following ASCII characters can be
transferred: 5bit: not allowed: 6bit: 20...3Fh, 7bit: 20...7Fh, 8bit:
20...FFh.
n The effective data, which includes all the characters between Start
and End are transferred to the CPU when the End has been
received.
n When data is send from the CPU to a peripheral device, any user
data is handed to the FC/SFC 217 (SER_SND) and is transferred
with added Start- and End-ID to the communication partner.
n You may work with 1, 2 or no Start- and with 1, 2 or no End-ID.
n If no End-ID is defined, all read characters are transferred to the
CPU after a parametrizable character delay time (Timeout).
As Start-res. End-ID all Hex values from 01h to 1Fh are permissible.
Characters above 1Fh are ignored. In the user data, characters below
20h are not allowed and may cause errors. The number of Start- and
End-IDs may be different (1 Start, 2 End res. 2 Start, 1 End or other
combinations). For not used start and end characters you have to
enter FFh in the hardware configuration.
Message structure:
The 3964R procedure controls the data transfer of a point-to-point link
between the CPU and a communication partner. The procedure adds
control characters to the message data during data transfer. These
control characters may be used by the communication partner to
verify the complete and error free receipt.
The procedure employs the following control characters:
n STX: Start of Text
n DLE: Data Link Escape
n ETX: End of Text
n BCC: Block Check Character
n NAK: Negative Acknowledge
You may transfer a maximum of 255byte per message.
Procedure
3964
VIPA System 300SDeployment PtP communication
Protocols and procedures
HB140 | CPU | 315-4PN33 | GB | 14-43 96