Specifications

Ethernet Head Station STL-ETH1 (Ethernet)
4 - 8
MITSUBISHI ELECTRIC
The input module data can be read by the CPU and by the fieldbus side. Likewise, data can be written
to the output modules from the CPU and the fieldbus side.
In addition, all output data is mirrored in the STL-ETH1 to a memory area with the address offset 0200
H
and 1000 H . This allows output values to be read back in by adding 0200 H or 1000 H to the MODBUS
address.
Addressing
Module inputs and outputs in a head station are addressed internally as soon as they are started. The
order in which the connected modules are addressed depends on the type of module that is con-
nected (input module, output module). The process image is formed from these addresses. The phys-
ical arrangement of the I/O modules in the fieldbus node is arbitrary.
Addressing first references complex modules (modules that occupy several bytes) in accordance with
their physical order downstream of the head station; i.e., they occupy addresses starting from word 0.
Following these is the data for the remaining modules, compiled in bytes (modules that occupy less
than one byte). In this process, byte by byte is filled with this data in the physical order. As soon a com-
plete byte is occupied by the bit oriented modules, the process begins automatically with the next
byte.
Fig. 4-8: Memory areas and data exchange
NOTES Hardware changes can result in changes of the process image!
If the hardware configuration is changed and/or expanded; this may result in a new process image
structure. In this case, the process data addresses also change. If adding modules, the process data
of all previous modules has to be taken into account.
Observe process data quantity!
For the number of input and output bits or bytes of the individual IO modules please refer to the
corresponding I/O module description in the appendix of this manual.
Head station STL-ETH1 (Ethernet)
Fieldbus master
Memory area for
input data
Memory area for
output data
Word 0
Word 255
Input
modules
Word 0
Word 255
Output
modules
I/O modules
IO