11Write Bytes Function (4401) - GE VersaMax PLC User Manual

address
address +1
address +2
address +3
address +4
address +5
address +6
address +7
address +8
address +9
address +10
address +11
Serial I/O / SNP / RTU Protocols
For public disclosure
12.4.11 Write Bytes Function (4401)
This operation can be used to transmit one or more characters to the remote device
through the specified serial port. The character(s) to be transmitted must be in a word
reference memory . They should not be changed until the operation is complete.
Up to 250 characters can be transmitted with a single invocation of this operation. The
status of the operation is not complete until all of the characters have been transmitted or
until a timeout occurs (for example, if hardware flow control is being used and the remote
device never enables the transmission).
12.4.11.1 Example Command Block for the Write Bytes
Function
VALUE VALUE
(decimal) (hexadecimal)
0006 0006
0000 0000
0008 0008
0000 0000
0000 0000
0000 0000
4401 1131
0030 001E
0005 0005
25960 6568
27756 6C6C
111 006F
Although printable ASCII characters are used in this example, there is no restriction on
the values of the characters which can be transmitted.
12.4.11.2 Operating Notes
Note Specifying zero as the Transmit time-out sets the time-out value to the amount of
time actually needed to transmit the data, plus 4 seconds.
Caution
MEANING
Data block length (includes characters to send)
NOWAIT mode
Status word memory type (%R)
Status word address minus 1 (%R0001)
Not used
Not used
Write bytes command
Transmit time-out (30 seconds). Refer to the
following note.
Number of bytes to write
'h' (68h), 'e' (65h)
'l' (6Ch), 'l' (6Ch)
'o' (6Fh)
If an Initialize Port (4300) COMMEQ is sent or a
Cancel Operation (4399) COMMREQ is sent in
either Cancel All or Cancel Write mode while this
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.
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