14
Remote I/O Installation and Programming Manual
3.2
Input Image Table Format
The Remote I/O Interface places two 16-bit words in the PLC input image table which are read by the PLC
controller. The Remote I/O Interface receives data from the indicator, then writes data and status information to
the input image table based on parameters specified on the previous discrete write command. A discrete read
command is performed when the PLC controller reads the data from the input image table.
The format of the input image table is shown in Table 3-7:
where:
v00–v15
16-bit signed integer value (v15 is the sign bit)
v16–v19
4 high-order bits of 20-bit unsigned integer
p
Polarity bit for 20-bit integer (0 = positive; 1 = negative). Not valid for 16-bit integers.
s00–s10
Status data
Value
Word 0 of the input image table is used to return
weight data to the PLC controller. For values returned
in 16-bit format, bit v15 serves as the sign bit. Values
returned in 20-bit format use word 0 and bits v16–v19
of word 1, with a polarity bit (word 1, bit 4) to indicate
the sign.
See Section 3.3 on page 15 for information about
interpreting bit shifted values in the input image table.
Polarity
The polarity bit is used to indicate the sign of values
returned in 20-bit format. This bit is not used for
16-bit values.
Status Data
Status data returned on a discrete read command can
be either remote function status data or batch function
status data, depending on the format specified on the
write command.
Status bits should be routinely checked
to ensure that incoming weight data is
valid and that communication with the
indicator is active.
For example, if communication with the indicator is
lost, the weight OK/weight invalid bit (status bit s12)
is set. Failure to monitor this bit can cause overflows
or accidents if conditional filling operations are based
on old data.
Table 3-8 shows the remote function status data
format.
Bit
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Word 0
v15
v14
v13
v12
v11
v10
v09
v08
v07
v06
v05
v04
v03
v02
v01
v00
Word 1
s10
s09
s08
s07
s06
s05
s04
s03
s02
s01
s00
p
v19
v18
v17
v16
Table 3-7. Input Image Table Format
!
Caution
Word 1
Bit
Status
Bit
Remote Function Status Data
Value=0
Value=1
05
s00
No bit shift
Bits shifted
06
s01
Reserved
07
s02
08
s03
Gross
Net
09
s04
No tare
Tare acquired
10
s05
Primary (LB)
Secondary (KG)
11
s06
Standstill
In motion
12
s07
Weight OK
Weight invalid /
Over-range
13
s08
Not zero
Center of zero
14
s09
Tare not entered
Tare entered
15
s10
Reserved
Table 3-8. Remote Function Status Data Format
DISCONTINUED
