Publication 1763-RM001C-EN-P - October 2009
322
ASCII Instructions
ABL - Test Buffer for
Line
Instruction Type: output
The ABL instruction is used to determine the number of characters in the
receive buffer of the specified communication channel, up to and
including the end-of-line characters (termination). This instruction looks
for the two termination characters that you configure via the channel
configuration screen. On a false-to-true transition, the controller reports
the number of characters in the POS field of the control data file. The
channel configuration must be set to ASCII.
Entering Parameters
Enter the following parameters when programming this instruction:
•
Channel
is the number of the RS-232 port, Channel 0.
•
Control
is the control data file. See page 313.
•
Characters
are the number of characters in the buffer that the
controller finds (0 to 1024). This parameter is read-only and resides
in word 2 of the control data file.
•
Error
displays the hexadecimal error code that indicates why the ER
bit was set in the control data file. See page 337 for error code
descriptions.
Addressing Modes and File Types can be used as shown below:
TIP
For information on the timing of this instruction, see the
timing diagram on page 336.
EN
DN
ER
ABL
Ascii Test For Line
Channel
0
Control
R6:0
Characters
1<
Error
0<
ABL
Execution Time for the ABL Instruction
Controller
When Instruction Is:
True
False
MicroLogix 1100
10.93
μ
s/character
11.43
μ
s
ABL Instruction Valid Addressing Modes and File Types
For definitions of the terms used in this table see Using the Instruction Descriptions on page 82.
Parameter
Data Files
(1)
Function Files
CS - Comms
IO
S -
I/O
DL
S
- Da
ta
L
o
g
Address
Mode
Address Level
O
I
S
B
T,
C
, R
N
F
ST
L
MG,
PD
RI/RIX
PLS
RTC
HS
C
PTO, P
W
M
STI
EII
BH
I
MMI
LCD
Imme
diate
Di
re
c
t
In
di
re
ct
Bi
t
Wo
rd
Long
W
o
rd
E
lem
en
t
Channel
•
•
Control
•
•
•
(1) The Control data file is the only valid file type for the Control Element.
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