Siemens S7-1200 - Fieldread (Read Field) and Fieldwrite (Write Field) Instructions

Basic instructions
7.6 Move operations
S7-1200 Programmable controller
240 System Manual, 03/2014, A5E02486680-AG
Table 7- 65 ENO status
ENO
Condition
Result
1
No error
All COUNT elements were successfully copied.
0 Either the source (IN) range or the destination (OUT)
range exceeds the available memory area.
Elements that fit are copied. No partial
elements are copied.
7.6.2
FieldRead (Read field) and FieldWrite (Write field) instructions
Note
STEP 7 V10.5 did not support
a variable reference as an array index or multi-dimensional
arrays. The FieldRead and FieldWrite instructions were used to provide variable array index
opera
tions for a one-dimensional array. STEP 7 V11 and greater
do support
a variable as an
array index and multi
-dimensional arrays. FieldRead and FieldWrite are included in STEP 7
V11 and greater for backward compatibility with programs that have used these in
structions.
Table 7- 66 FieldRead and FieldWrite instructions
LAD / FBD
SCL
Description
value :=
member[index];
FieldRead reads the array element with the index
value INDEX from the array whose first element in
specified by the MEMBER parameter. The value of
the array element is transferred to the location
specified at the VALUE parameter.
member[index] :=
value;
WriteField transfers the value at the location specified
by the VALUE parameter to the array whose first
element is specified by the MEMBER parameter. The
value is transferred to the array element whose array
index is specified by the INDEX parameter.
1
For LAD and FBD: Click the "???" and select a data type from the drop-down menu.