Specifications

Process Images Appendix
Quick Start Guide for the MELSEC STlite Series A - 11
STL-DA4-I (ID number 51205040)
The analog output module STL-DA4-I (four channels, 4 to 20 mA) requires 16-bit data and 8 status bits
per channel.
The digitalized output value is transmitted in a data word (16 bits) as output byte 0 (low) and output
byte 1 (high) via the process image of the head station. This value is represented with a 12 bit reso-
lution on the bits b3 to b14. The three least significant bits (b0 to b2) are not parsed.
Some fieldbus systems can process the status information using by means of a status byte. However,
processing of the status byte via the head station is optional, which means that accessing or parsing
the status information depends on the fieldbus system.
X: Not relevant

Broken wire or inadmissible load combination

The ERROR-LED will also be ON.
NOTE
Although the bits b0 to b2 are not relevant, they can be used for the ease of programming (see
table below). The resulting output error will only be marginal.
Fig. A-14: Process image of the analog output module STL-DA4-I
Output
[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 Output value X X X
4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0000 H 0 00 H
8 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1FFF H 8191 00 H
12 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3FFF H 16383 00 H
16 0 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 5FFF H 24575 00 H
20 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 7FFF H 32767 00 H
Error

Undefined 40 H

Tab. A-10: Process values and corresponding output values for the STL-DA4-I
b15 b14 b13 b12 b11 b10 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0
Output byte 1
XXX0/10/10/10/10/10/10/10/10/10/10/10/1X
Output byte 0
X: Not used