There are some program block in my TIA portal,is it possible to access it with Python-snap7?I am using plc 1200

[hackaming]

There are some program block in my TIA portal,is it possible to access it with Python-snap7?I am using plc 1200

[gijzelaerr]

Yes, you can access data blocks on an S7-1200 with python-snap7. Make sure PUT/GET communication is enabled in TIA Portal (PLC properties → Protection & Security → Connection mechanisms → Permit access with PUT/GET).

For data blocks (DB), use db_read() / db_write():

import snap7

client = snap7.Client()
client.connect("192.168.0.1", 0, 1)

# Read 100 bytes from DB1 starting at offset 0
data = client.db_read(1, 0, 100)

Note: the DB must have Optimized block access disabled in TIA (right-click DB → Properties → Attributes → uncheck "Optimized block access"), otherwise S7 protocol cannot address the data by byte offset.

For program blocks (OB, FC, FB), you can upload the compiled block bytecode with upload() or full_upload():

from snap7.type import Block

data = client.full_upload(Block.FC, 1)

This gives you the raw block binary — useful for backup/comparison, but not a human-readable TIA project export. python-snap7 cannot read the TIA Portal project file itself, only what is on the PLC over the network.

[IDavinciCode]

One correction on the program-block part, for S7-1200 specifically.

The data side above is right: with PUT/GET enabled and "Optimized block access" off, db_read()/db_write() work on an S7-1200, and so do inputs, outputs and markers.

Reading program blocks (OB/FB/FC) is a different matter. The project's own documentation now says to treat block upload and download on S7-1200/1500 as unsupported unless you have verified it on your CPU and firmware (doc/plc-support.rst, "Feature Availability"). The hardware report in #907 shows why: a CPU 1212C, firmware V4.7.3, with PUT/GET enabled, serves DB reads and writes but refuses upload() with

S7ProtocolError class 0x81, code 0x04: This service is not implemented on the module

doc/error-reference.rst lists the same error for block upload on an S7-1200.

Even on a CPU that allows it, an upload gives you the compiled block as raw bytes, not SCL/LAD source, and blocks with know-how protection stay protected. doc/limitations.rst says the same: a full project backup requires TIA Portal.

In practice, for an S7-1200:

• Values the program uses: put them in a non-optimized DB (or M/I/Q) and read them with db_read() / read_area().
• The program logic itself: it is not readable through python-snap7. Take it from the TIA Portal project. If you need it in a script, TIA Portal Openness can export blocks from the project.

[gijzelaerr]

Thanks @IDavinciCode, you're right, and my earlier answer was wrong about program blocks. Block upload isn't supported on S7-1200/1500 over classic S7 (see doc/plc-support.rst; hardware report #907 shows the 0x81/0x04 refusal). Please use the correction above: put the values you need in a non-optimized DB and read them with db_read(), and take the program logic from the TIA Portal project. Marking that comment as the answer.