Specifications

Process Images Appendix
Quick Start Guide for the MELSEC STlite Series A - 5
STL-AD2-I (ID number 51205047)
The two-channel analog input module STL-AD2-I (for currents from 4 to 20 mA) transmits a 16-bit
measured value and 8 status bits per channel. Accessing the status byte depends on the fieldbus sys-
tem being used.
The digitalized measured value is transmitted in a data word (16 bits) as input byte 0 (low) and input
byte 1 (high) into the process image of the head station/controller.
This value is represented with a 12 bit resolution on bit b3 to b14. The least significant bit b0 is set (1)
when the range of measurement is overranged. Both bits b0 and b1 are set in case of measurement
range underflow or broken wire.
X: Not used; UV: Measuring range underflow, OV: Measuring range overflow
* In this cases the ERROR-LED of the corresponding channel is lit.
Fig. A-8: Process image of the analog input module STL-AD2-I
NOTE The representation of the process data of some I/O modules in the process image depends on the
fieldbus head station used.
Please take this information as well as the particular design of the respective control/status bytes
included in the description concerning the process image of the corresponding head station.
Input
[mA]
Numerical value
Status
byte
(Hex.)
Binary
Hexa-
decimal
Decimal15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
X Measured value X UV OV
<0 Not possible (Reverse voltage protection)
2 to 3.9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0003 H 3 41 H *
<4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0000 H 0 00 H
4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0000 H 0 00 H
6 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1000 H 4096 00 H
8 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 2000 H 8192 00 H
10 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 3000 H 12288 00 H
12 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4000 H 16384 00 H
14 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 5000 H 20480 00 H
16 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 6000 H 24576 00 H
18 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 7000 H 28672 00 H
20 0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 7FF8 H 32760 00 H
>20 0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 7FF9 H 32761 42 H
20.1 to
22
0 1 1 1 1 1 1 1 1 1 1 1 1 0 0 1 7FF9 H 32761 42 H *
Tab. A-4: Input values and corresponding process values for the STL-AD2-I
b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
Input byte 1
UV
OV
UVX0/10/10/10/10/10/10/10/10/10/10/10/1X
Input byte 0
X: Not used
UV: Measuring range underflow
OV: Measuring range overflow