Device exchange and spare parts compatibility
D.1 Exchanging a V3.0 CPU for a V4.2 CPU
Requirement to recompile program blocks
After exchanging a V3.0 CPU for a V4.2 CPU, you must recompile all program blocks before
you can download them to the V4.2 CPU. Additionally, if any of the blocks have know-how
protection (Page 213) or copy protection bound to a PLC serial number (Page 214), you
must remove the protection before you compile and download the blocks. (You do not,
however, need to deactivate copy protection bound to a memory card.) After a successful
compile, you can reconfigure the know-how protection and/or PLC serial number copy
protection. Note that if your project includes any blocks with know-how protection that an
OEM (Original Equipment Manufacturer) provided, you must contact the OEM to provide
V4.2 versions of those blocks.
In general, Siemens recommends that you recompile the hardware configuration and
software in STEP 7 and download to all devices in your project after the device exchange.
Correct any errors that compiling the project finds, and recompile until you have no errors.
Then, you can download the project to the V4.2 CPU.
S7-1200 V3.0 projects might not fit in S7-1200 V4.2 CPUs
S7-1200 V4.0 and later added a reserve area of 100 bytes to each DB to support download
without reinitialization.
You can remove the 100-byte reserve area from DBs prior to attempting to download a V3.0
project to a V4.2 CPU.
To remove the 100-byte reserve area, follow these steps before you perform the device
exchange:
1. From the TIA Portal main menu, select the Options > Settings menu command.
2. From the navigation tree, open the PLC programming > General node.
3. In the "Download without reinitialization" area, set the memory reserve to 0 bytes.
1576
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK