Automating Manufacturing Systems - Process Control and ...

plc function ref - 34.40
ARD, ARL - Ascii ReaD, Ascii Read Line
Description:
A
ARD
ASCII READ
Channel
Dest
Control
String Length
Characters Read
0
ST10:0
R6:10
15
The ARD instruction will read characters and write them to a string. In
this example the characters are read from channel 0 and written to
’ST10:0’. All of the characters in the buffer, up to 15 in total, will be
removed and written to the string memory. The number of characters
will be stored in ’R6:10.POS’.
The ARL function is similar to the ARD function, except that the end-ofline
values ’CR’ or ’LF’ will mark the end of a line. With the parameters
above the string will be copied until 15 characters are reached, or
there are fewer than 15 characters, or an end-of-line character is
found.
Status Bits:
EN
DN
ER
UL
EM
EU
enable - will be set while the instruction is enabled
done - will be set when then string has been read
error - will be set if an error has occurred
unload -
empty - will be set if no characters were found
queue -
Registers: POS the number of characters copied
Available on: Micrologix, PLC-5