Appendix - Siemens SINUMERIK 840 Planning Manual

3 Interface Modules
3.3.1 3964R procedure
If connection establishment is successful, the useful information contained in the output buffer
are sent to the peripheral unit at the selected data transmission rate. The peripheral unit
monitors the intervals in which the incoming characters arrive.The interval between two
characters must not be longer than the character delay period (ZVZ).
Every DLE character retrieved from the buffer is sent as two DLE characters.
After the buffer content has been transmitted, the transmit driver adds the characters DLE,
ETX (end-of-text) and BCC (block check character) to specify end-of-text and waits for an
acknowledgement character.
The data block has been received without error if the peripheral unit transmits the DLE
character (acknowledgement) within the timeout period. If the peripheral unit responds with
NAK, any other character (except DLE) or a mutilated character, or if the acknowledgement
delay (timeout) elapses without response, the driver repeats transmission of the complete data
block. With the CP 315, the number of transmission attempts can be configured. After several
failed attempts to send the data block, the procedure aborts the process and the driver sends
the identification character "procedure error".
If the peripheral unit sends the NAK character during a transmission session, the driver
terminates the block and repeats the procedure as described above.
Example:
Example of an error-free data traffic using the 3964R procedure:
SINUMERIK 8X0 with CP 315
3964R procedure
1st character
"
"
"
nth character
DLE
ETX
BCC
For more detailed information on data reception using 3964R, initialization conflict, character
frames, data protection and monitoring times please refer to the procedure description in the
appendix (see Section 9, Appendix).
3–16
(request to send)
(acknowledgement)
DLE (NAK)
(without error)
DLE (NAK)
© Siemens AG 1989 All Rights Reserved
peripheral unit
(e.g. read/write station)
(end of transmission)
6FC5 197-0AB20-0BP0
SINUMERIK 840/880 (PJ)
06.91