IV25101A_e.DOC / Feb-08
Page 17 / 25
SSI Baud Rate:
Sets the communication speed of the SSI interface with SSI encoders.
Setting range: 100 Hz to 1MHz.
You are free to set any desired frequency between 0.1 kHz and 1000.0 kHz. For technical
reasons however, in the upper frequency range with Master operation, the unit will only
generate one of the following frequencies accurately:
1 000,0 kHz
888,0 kHz
800,0 kHz
727,0 kHz
666,0 kHz
615,0 kHz
571,0 kHz
533,0 kHz
500,0 kHz
470,0 kHz
444,0 kHz
421,0 kHz
400,0 kHz
380,0 kHz
363,0 kHz
347,0 kHz
333,0 kHz
320,0 kHz
307,0 kHz
296,0 kHz
285,0 kHz
275,0 kHz
266,0 kHz
258,0 kHz
250,0 kHz
With Master operation, other settings will result in generation of the next upper or lower value
according to above list. With all settings < 250.0 kHz the error between set rate and generated
rate becomes negligible.
It is mandatory to set the Baud rate also with Slave operation. In this case, however, the
setting serves only to determine the pause time for correct synchronization (pause is detected
after 4 clock cycles). The unit automatically synchronizes with every remote clock signal within
the specified Baud rate range.
SSI Wait Time:
This register sets the waiting time between two SSI telegrams in a range from 0.001 to 99.999
sec. In normal operation, due to processor cycle times, the real time may vary by 512
μ
sec. with
respect to the preset time: The fastest sequence possible is 1.3
μ
sec with a setting of 0.000.
With Slave operation mode, the distance of the SSI protocols depends on the remote Master
and the SSI Wait Time specifies the distance of evaluation data strings. Setting to 100 msec
results in evaluation of one telegram only every 100 msec, even though the Master may have
transmitted many telegrams more.
Especially with applications of closed-loop control loops, it may be of advantage to have
equidistant updating of the analogue output (DIL switch 7 = OFF). This is possible with Master
mode only, and the Wait Time setting (must be >0) directly corresponds to the time pattern of
updates.
The subsequent drawing explains the timing with use of equidistant update mode with a SSI
Wait Time setting of 3 msec.
