Structure Of A Uss Telegram - Siemens SINAMICS CU240S DP-F Operating Instructions Manual

Communication
6.6 Communication via USS
6.6.3

Structure of a USS Telegram

Description
The following figure shows the structure of a typical USS telegram.
Figure 6-16
Variable length telegrams and fixed length telegrams can both be used. This can be selected
using parameters P2012 and P2013 to define the PZD and PKW lengths.
The most common fixed length application is shown below:
STX
LGE
ADR
use data
BCC
Sum :
Start Delay
The length of the start delay is at least the time of two characters and depends on the
baudrate.
Table 6-40
Baudrate in bit/s
9600
19200
38400
57600
115200
Note: The time between characters must be smaller than the start delay.
178
Header
STX LGE
Structure of USS telegram
1 Byte
1 Byte
1 Byte
PKW 8 Bytes (4 Words: PKE + IND + PWE1 + PWE2)
PZD 4 Bytes (2 Words: PZD1 + PZD2)
1 Byte
16 Bytes (LGE indicates 14 bytes as STX and LGE are not counted in LGE)
Length of start delay
Transfer time per character (= 11 bit)
1.146 ms
0.573 ms
0.286 ms
0.191 ms
0.059 ms
n use data
ADR 1 . 2 .
Transfer time per bit
104.170 µs
52.084 µs
26.042 µs
17.361 µs
5.340 µs
Operating Instructions, 07/2008 - FW 3.2, A5E00766042B AD
Trailer
: : :
n . BCC
Min. Start Delay
> 2.291 ms
> 1.146 ms
> 0.573 ms
> 0.382 ms
> 0.117 ms
Control Units CU240S