Siemens SIMATIC NET PROFIBUS - Manual (Page 55)

Topologies of SIMATIC NET PROFIBUS Networks
2-29
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Uses
The PROFIBUS-DP/RS-232C link is a converter between an RS-232C (V.24)
interface and PROFIBUS-DP. Devices with an RS-232C interface can be linked to
PROFIBUS-DP with the DP/RS-232C link. The DP/RS-232C link supports the
procedures 3964 R and free ASCII protocol.
Configuration
with STEP 7
Master
S7-400
SIEMENS DP/RS-232C Link
Device
PROFIBUS-DP
RS-232C
Serial procedure
PROFIBUS
LAN cable
Figure 2-19 Example of a Configuration with DP/RS-232C Link
How the DP/RS-232C Link Works
The PROFIBUS-DP/RS-232C link is connected with the device over a
point-to-point connection. The PROFIBUS-DP/RS-232C link converts to the
PROFIBUS-DP protocol. Consistent data are transferred in both directions. A
maximum of 224 bytes of user data can be transferred per frame.