Connection to a fieldbus
6.4 Communication via RS485
Inverter with CU240B-2 and CU240E-2 Control Units
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
143
The slave only responds after the response delay has expired.
: : :
: : :
: : :
: : :
67; /*( $'5
Q
%&&
67; /*( $'5
%&&
67; /*(
%&&
Q
6WDUWGHOD\
6WDUWGHOD\
5HVSRQVHGHOD\
5HTXHVWIURPPDVWHU
5HTXHVWIURP
WKHPDVWHU
6ODYHUHVSRQVH
Figure 6-18 Start delay and response delay
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 Duration of the start delay
Baud rate in bit/s
Transmission time per character (= 11 bits)
Min. start delay
9600
1.146 ms
> 2.291 ms
19200
0.573 ms
> 1.146 ms
38400
0.286 ms
> 0.573 ms
57600
0.191 ms
> 0.382 ms
115200
0.059 ms
> 0.117 ms
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:
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 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.