Siemens SINAMICS G120XA, Operating Instructions Manual

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Baud rate in bit/s Transmission time per character (= 11 bits) Min. start delay
38400 0.286 ms > 0.573 ms
57600 0.191 ms > 0.382 ms
115200 0.095 ms > 0.191 ms
The character delay time must be shorter than the start delay.
Telegram monitoring of the master
With your USS master, we recommend that the following times are monitored:
● Response delay:
Response time of the slave to a request from the master
The response delay must be < 20 ms, but longer than the start delay
● Telegram runtime:
Transmission time of the response telegram sent from the slave
Telegram monitoring of the converter
The converter monitors the time between two requests of the master. Parameter p2040 defines
the permissible time in ms. If a time p2040 ≠ 0 is exceeded, then the converter interprets this
as telegram failure and responds with fault F01910.
150% of the residual runtime is the guide value for the setting of p2040, i.e. the telegram
runtime without taking into account the character delay times.
For communication via USS, the converter checks bit 10 of the received control word 1. If the
bit is not set when the motor is switched on ("Operation"), the converter responds with fault
F07220.
Parameters
Parameter Description Factory setting
p2040 Fieldbus interface monitoring time 100 ms
6.2.4.7 USS parameter channel
Structure of the parameter channel
Depending on the setting in p2023, the parameter channel has a fixed length of three or four
words, or a variable length, depending on the length of the data to be transferred.
1. and 2nd word contain the parameter number and index as well as the type of job (read or
write). The other words of the parameter channel contain parameter contents. The parameter
contents can be 8-bit values, 16-bit values (such as baud rate) or 32-bit values (e.g. CO
parameters). The parameter contents are entered right justified in the word with the highest
number. Words that are not required are assigned 0.
Bit 11 in the 1st word is reserved and is always assigned 0.
The diagram shows a parameter channel that is four words long.
Advanced commissioning
6.2 Drive control
SINAMICS G120XA converter
174
Operating Instructions, 03/2019, FW V1.0, A5E44751205B AB