Ssi Absolute Encoder - Siemens SIMATIC ST-1500 Function Manual

Using the SSI_Absolute_Encoder technology object
4.4 Configuring SSI_Absolute_Encoder
4.4.3

SSI absolute encoder

Frame length
With the parameter assignment of the frame length, you specify the number of bits of an SSI
frame of the SSI absolute encoder (Page 24) used. You can find the frame length of your
SSI absolute encoder in the data sheet of the encoder. Special bits are also included in the
frame length. A parity bit does not count in the frame length.
A frame length of between 10 bits and 40 bits is permitted. The default setting is "13 Bit".
You can find two examples of the SSI frame format at Examples of the frame format
(Page 153).
Code type
You use the parameter assignment of the code type to specify whether the encoder supplies
Dual code or Gray code.
You can select from the following options:
Code type
Gray
(default)
Dual
Transmission rate
With the parameter assignment of the transmission rate, you specify the data transmission
rate between the technology module and the SSI absolute encoder. You can select from
several options between 125 kHz and 2 MHz. The default setting is "125 kHz".
The maximum transmission rate depends on the cable length and the technical
specifications of the SSI absolute encoder. For additional information, refer to the product
manual of the TM PosInput and the encoder description.
Monoflop time
With the parameter assignment of the monoflop time, you specify the idle time between two
SSI frames.
The configured monoflop time must be at least equal to the monoflop time of the SSI
absolute encoder used. You can find this value in the technical specifications of the SSI
absolute encoder.
You can select from the following options:
● Automatically (default)
● 16 µs
● 32 µs
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Meaning
The gray-coded position value returned by the SSI absolute encoder is convert-
ed to dual code.
The value returned by the SSI absolute encoder is not converted.
Counting, measurement and position detection
Function Manual, 12/2017, A5E32009889-AG