step-7 plc s7-216 internal flags


Thread Starter


Dear sir,
Can anybody guide regarding selection of internal
flag, variable word, double data word. How many flag datawords are avilable in s7-216.
If i use v0.0 as flag bit then can i use vw0 as
a data register. If i use VD0 as vaiable word then
can i use vw0 as a different data register or it is just a part of vd0.

My project requires following number of flag and
data register.

Internal flag:Around 2000.
Vaiable word :Around 4000
Double data word:Around 300.
Wheather s7-216 is suitable for above Project.
Pl advise as early as possible.

Daniel Chartier

Hello Ashok;
The S7-226 CPUs only give you access to 32 bytes of internal flags (256 flags, from M0.0 to M31.7), which is low for your needs. Howerver, V-memory can be accesses in bit addressing (V10.0, in byte/word/dword addresing (VB15, VW224, VD126).
If you choose a CPU 226XM (extended memory), you will have access to 5KB of V-memory (VB0 to VB10239) that you can organize to your needs; for example:

2000 flags: from V0.0 to V 249.7
4000 words: from VW250 to VW 8248 (2 bytes/word)
300 Dwords: from VD8250 to VD9450 (4 bytes/Dword)

Your application should run in this memory field.
For more info, dowwmload le S7200N_e.pdf manual from the Siemens support website.
Hope this helps,
Daniel Chartier