Using an experimental arrangement, the resulting cycle times of the measurement depending on the different access points of the S7 CPU were measured and evaluated.
Configuration of the PLC:
-
S7-400 CPU 416 2DP
-
Cycle OB1: 6 ms to 10 ms
-
ibaPDA measurement time base: 1 ms
|
Number of signals |
MPI adapter (COM) 38.4 kBd |
MPI adapter (USB, DeltaL) 38.4 kBd |
MPI adapter (USB, Siemens) |
CP5611 PROFIBUS,12 Mbit/s |
TCP/IP |
L2B *) |
|---|---|---|---|---|---|---|
|
1 |
108 |
52 |
40 |
24 |
12 |
1 |
|
11 |
130 |
62 |
51 |
26 |
13 |
1 |
|
21 |
155 |
78 |
54 |
27 |
13 |
1 |
|
32 |
160 |
78 |
55 |
27 |
13 |
1 |
|
42 |
171 |
78 |
56 |
27 |
14 |
1 |
|
53 |
189 |
94 |
60 |
29 |
15 |
1 |
|
64 |
280 |
140 |
90 |
42 |
18 |
1 |
*) 1 ms is the ibaPDA time base which is supported by iba cards such as ibaCom-L2B-8-8, for example. But the actual measurement cycle, in fact, is depending on the PROFIBUS cycle time (with 2 slaves: 0.98 ms; with 8 slaves: 1.6 ms, provided 12 Mbit/s) and the program cycle (OB1 or OB35)
