ASCII Driver S5-95U, Second Serial Interface
4.3 Coordination Bytes for Use of the ASCII Driver
The ASCII driver monitors data traffic and stores status and error messages in two bytes, the
”send” (KBS) and ”receive” (KBE) coordination bytes.
The following display shows the structure of the two coordination bytes.
Figure 4-6 Structure of the Coordination Bytes
”Send” coordination byte (KBS) (flag byte or high-order byte in the data word)
Sending allowed
Is set by the user and reset by the ASCII driver when the send procedure in
terminated.
If a positive-going edge occurs in this bit, the send procedure is activated.
Error message ( Table 4-1)
2
7
2
0
R R RRR RW/R R
”Receive” coordination byte (KBE) (flag byte or high-order byte in the data word)
Receiving allowed
Is set by the user and reset by the ASCII driver after receiving with or without errors.
Error message ( Table 4-1)
R: Read Only (bit may only be read)
W/R: Write / Read (bit may be read and overwritten)
2
7
2
0
R R RRR RW/R R
Note
The bits in the coordination bytes can be set and/or reset by the operating system after
every instruction irrespective of the PLC scan cycle. That is, a repeated scan of a
coordination bit in a program cycle can lead to different results. (Caution during pulse
edge evaluation!)
4-6
EWA 4NEB 812 6095-02
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