Siemens Simatic S7-400 Equipment Manual

2.5.2 Block Checksum
Block Checksum
With the 3964(R) transmission protocol, data integrity is increased by the additional sending of
a block check character (BCC).
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Figure 2-13 Block Checksum
The block checksum is the even longitudinal parity (EXOR operation on all data bytes) of a sent
or received block. Its calculation begins with the 󹪝rst byte of user data (󹪝rst byte of the message
frame) after the connection setup, and ends after the DLE ETX code on connection release.
Note
If DLE duplication occurs, the DLE code is accounted for twice in the BCC calculation.
Basic Principles of Serial Data Transmission
2.5 Data Transmission with the 3964(R) Procedure
Point-to-point connection CP 440 Installation and Parameter Assignment
Equipment Manual, 03/2022, A5E00057742-AE 37

Siemens Simatic S7-400 Specifications

General

Programming Language	STEP 7 (LAD, FBD, STL, SCL, GRAPH)
Communication Interfaces	MPI, PROFIBUS
Power Supply	24 V DC, 120/230 V AC (Power supply modules are separate and chosen based on system requirements)
Operating Temperature	0°C to 60°C
Mounting	Rack mounting
Processor	CPU 412-1, CPU 414-2, CPU 416-2, CPU 417-4 (Different CPUs offer varying performance and features)
Relative Humidity	5 to 95% (non-condensing)