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S5-95F on SINEC L1
Coordinating Data Interchange via the User Valid Byte
The User Valid Byte is used to coordinate data interchange (similar to the KBE and KBS for
nonfailsafe data interchange).
User Valid Byte
7
6
5
4
3
Coordinating the Frame Sequence in the SINEC L1 Receiver
The S5-95F does not transmit a "new" frame until the receiver's operating system has accepted the
data in the "old" frame. The transmitter, however, receives no acknowledgement as to whether the
receiver's user program evaluated the frame.
Because the S5-95F erases the contents of the Receive Mailbox in the event of a power failure, a
frame is lost when the receiver's operating system received it but the user program failed to
evaluate it before the power failed. If your automated process cannot tolerate frame losses, you
must develop your own acknowledgement system for monitoring the frame sequence at the user
level. This, in turn, requires a data path from the receiver to the transmitter.
Safety Note
SINEC L1 nodes receive no acknowledgement indicating whether a valid frame was
received and subsequently evaluated by the user program. If your automated process
requires failsafe frame coordination, you must use an acknowledgement system to
monitor the frame sequence.
13-16
2
1
0
Send mailbox coordination for data path 1
Receive mailbox coordination for data path 1
Send mailbox coordination for data path 2
Receive mailbox coordination for data path 2
Internal control bits, not accessible to user
S5-95F
EWA 4NEB 812 6210-02
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