Ascii Mode - Siemens SIMATIC S5 CP 521 Manual

CP 521
4.2.2

ASCII Mode

Operation may be interrupted for various reasons in ASCII mode. The following
table lists the effects of the faults.
Table 4-5. Interruptions in Operation (ASCII Mode)
Fault Comment
CPU stops
POWER OFF
(CPU)
Battery backup
Fault in CP-
peripheral or
POWER OFF
(peripheral
device)
Note:
If you operate the RS-232-C (V.24) interface without handshaking (Handshake
OFF), the CP 521 cannot detect a break in the connection between the CP and
the peripheral device.
GWA 4NEB 812 6030-02b
Data traffic continues between CP and
peripheral device. This can lead to
overflow of the Receive mailbox.
Send and receive message data are lost
available
Clock data is retained
not available
Clock data is lost
Data is corrupted during transmission
(in both directions)
CP error message
• Character delay time error after
character time out
• Peripheral device not ready after 20s
Notes on Operation
Effect
4-5