Siemens SINAMICS G120 CU240B-2 Operating Instructions Manual page 143

The slave only responds after the response delay has expired.
: : :
Figure 6-18
The duration of the start delay must at least be as long as the time for two characters and
depends on the baud rate.
Table 6- 27
Baud rate in bit/s
9600
19200
38400
57600
115200
Note: The character delay time must be shorter than the start delay.
Telegram monitoring of the master
The USS master must monitor the following times:
 Response delay:
 Telegram runtime:
Telegram monitoring of the inverter
The inverter monitors the time between two requests of the master. Parameter p2040
defines the permissible time in ms. If this time is exceeded, it is interpreted as a telegram
failure and results in fault message 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.
There is no monitoring for p2040 = 0.
If the USS is configured as a command source for the drive and p2040 is not zero, bit 10 of
the received control word 1 is checked. If the bit is not set, then fault message F07220 is
immediately output.
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
: : :
Start delay and response delay
Duration of the start delay
Transmission time per character (= 11 bits)
1.146 ms
0.573 ms
0.286 ms
0.191 ms
0.059 ms
Response time of the slave to a request from the master
The response delay must be < 20 ms, but longer than the start
delay
Transmission time of the response telegram sent from the slave
Connection to a fieldbus
6.4 Communication via RS485
: : :
Min. start delay
> 2.291 ms
> 1.146 ms
> 0.573 ms
> 0.382 ms
> 0.117 ms
: : :
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