Ethernet Communication (ISO on TCP) between SIMATIC S5 and
SIMATIC S7-1500 Controllers
Entry-ID: 109482475, V1.2, 07/2019
© Siemens AG
2019 All rights reserved
Data are requested from a S7-1500 via the CP1430 TCP by means of a FETCH
request of the SIMATIC S5.
The S7-1500 /CP1543-1 answers by sending the FETCH request with the requested
data including a positive acknowledgment to the CP1430 TCP. Otherwise, the
acknowledgment of the FETCH response by the CP1543-1 is negative. The data are
transferred from the CP1430 TCP to the data block of the SIMATIC S5-CPU via the
RECEIVE ALL handling block.
Via HTB SEND (RW), the SIMATIC S5 sends a WRITE request to the CP1430 TCP
with the data to be written to the CP1543-1. This one immediately forwards the data
to the corresponding data block. The data are transferred from the SIMATIC S5-
CPU (data block) to the CP1430 TCP via the SEND ALL handling block.
If the data have been successfully transmitted, the CP1543-1 responds with a
positive acknowledgement. Otherwise, the acknowledgment of the WRITE request
by the CP1543-1 is negative.
2.2.2 Communication program in the SIMATIC S7-1500
Overview
The following blocks contain the communication program in the S7-1500 CPU. In
this communication scenario, the S7-1500 is passive. No active communication
blocks are required.
OB 1
Main
OB 100
Startup
FC40 FWData-
Management
ComWriteDB
ComFetchDB
User
block
Data blocks
Function
A FETCH and a WRIE connection are established via a communication list in the
CP1543-1. Thus, a read and write access to the data areas of the S7-1500 CPU
can be set up. To detect the ongoing data access operations in the S7-1500, a
count value is written from the SIMATIC S5 to the S7-1500 (WRITE function),
incremented by +1 and made available in the FETCH data area. In the next
communication cycle, the increased value will be read by the SIMATIC S5 via the
FETCH connection.