12.4.9 Cancel Commreq Function (4399)
This function cancels the current operations in progress. It can be used to cancel both read
operations and write operations.
If a read operation is in progress and there are unprocessed characters in the input buffer,
those characters are left in the input buffer and available for future reads. The serial port
is not reset.
12.4.9.1 Example Command Block for the Cancel Operation
Function
VALUE
(decimal)
VALUE
(hexadecimal)
MEANING
address 0002 0002
Data block length (2)
address +1 0000 0000 NOWAIT mode
address +2 0008 0008
Status word memory type (%R)
address +3 0000 0000
Status word address minus 1 (%R0001)
address +4 0000 0000 Not used
address +5 0000 0000 Not used
address +6 4399 112F
Cancel operation command
address +7 0001 0001
Transaction type to cancel
1. All operations
2. Read operations
3. Write operations
12.4.9.2 Operating Notes
This function does not update the status of words of the cancelled COMMREQs.
Caution
If this COMMREQ is sent in either Cancel All or
Cancel Write mode when a Write Bytes (4401)
COMMREQ is transmitting a string from a serial
port, transmission is halted. The position within the
string where the transmission is halted is
indeterminate. In addition, the final character
received by the device the CPU is sending to is also
indeterminate.
12.4.10 Autodial Function (4400)
This feature allows the VersaMax CPU to automatically dial a modem and send a
specified byte string.
To implement this feature, the port must be configured for Serial I/O.
For example, pager enunciation can be implemented by three commands, requiring three
COMMREQ command blocks:
Autodial: 04400 (1130h) Dials the modem.
Write Bytes: 04401 (1131h) Specifies an ASCII string, from 1 to 250 bytes in length,
to send from the serial port.
Serial I/O / SNP / RTU Protocols GFK-1503E User Manual 243
For public disclosure
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