Specifications

Head Station STL-PB1 (Profibus DP) Profibus DP
Quick Start Guide for the MELSEC STlite Series 2 - 9
2.2.7 Local Process Image
After switching on, the head station STL-PB1 recognizes all connected STlite modules which supply
data or wait for data (data width/bit width > 0). Analog and digital I/O modules can be mixed.
The head station produces an internal process image from the data width and the type of STlite mod-
ule as well as the position of the STlite modules in the node. It is divided into an input and an output
data area.
The data of the STlite modules is separated for the local input and output process image in the
sequence of their position after the head station.
Allocation of the Input and Output Data
The process data is exchanged via the Profibus with the master.
● A maximum of 244 bytes of data is transmitted from the master to the node.
● The head station responds by returning a maximum of 244 bytes input data to the master.
Modules are configured according to their physical arrangement when projecting the node, which
can be taken over from a hardware catalogue of the configuration programs. The information cov-
ering the possible modules is contained in the GSD files.
NOTE
For the number of input and output bits or bytes of the connected STlite modules please refer to
the corresponding I/O module description in the appendix of this manual.
Fig. 2-10: Allocation of input and output data
Master (e.g. PLC)
CPU Profibus module
Master
addresses
Inputs
Outputs
Allocation list
Byte orientated allocation
generated on a PC
Inputs
Inputs
Outputs
Outputs
Profibus
Profibus
Inputs Inputs
Outputs Outputs
Bit and byte orien-
tated allocation gen-
erated automatically
by the STL-PB1
Allocation list
STL-PB1
Slave (STlite modules)