Technical data

8 Data Transmission by Direct Access to
Layer 2 Services
This chapter explains the following aspects:
➣ The devices and applications for which "data transmission by direct
access to layer 2 services" is suitable.
➣ How this type of data transmission functions.
➣ How this "link" is configured with COM 5430 TF/COM 5431 FMS and
how to assign parameters for the CP 5430 TF/CP 5431 FMS module
(example program in Section 8.4).
➣ The STEP 5 programs for this type of data transmission (example
program in Section 8.4).
➣ How to detect and remedy errors.
Areas of application for data transmission by direct access to layer 2
services
This type of data transmission is suitable for communication between two
SIMATIC S5 programmable controllers and remote PROFIBUS compatible
programmable controllers or field devices. SIMATIC S5 programmable
controllers can also communicate with each other with this type of data
transmission; however, for this situation, data transmission via S5-S5 links
is easier to implement (refer to Chapter 7).
With data transmission by direct access to layer 2 services you can transmit
or receive blocks of data with a maximum length of 242 bytes.
B8976060/02 Free Layer 2 Communication
8 - 1 Volume 1