SSI encoder interface
1 x SSI encoder interface
Synchronous Serial Interface is a standard that makes it possible to obtain absolute position data for a linear or angular position sensor.
- Accommodates an absolute encoder as per RS-422
- Supports 13 to 31 data bits
- Single-turn and multi-turn
- Encoder value normalization (the encoder value will only contain position-relevant bits)
- Direction indicator display
- Direction reversal
- Internal Gray-binary conversion
- Supports transmission rates of up to 2 MHz
- Encoder value parity check
- Digital 24 V input
- "Latch function" for freezing the current encoder value
- Comparator function with loadable reference values, configurable depending on the direction of rotation
- 24 V encoder supply
In terms of hardware, the module's SSI is implemented as a point-to-point connection as defined in the RS-422 standard. Moreover, in order to avoid ground loops, opto-isolators are used to achieve full electrical isolation.
Excellent noise immunity is ensured by the fact that the clock and data signals are sent through twisted pair cables using synchronous and symmetric transmission. The result is high reliability and robustness, making the module ideal for use in industrial environments.
The TB20 SSI encoder interface makes it possible to connect an SSI encoder with a transmission rate of up to 2 MHz. And, since the number of data bits is also adjustable, the module provides utmost flexibility in terms of supported encoder resolutions.
Data values can be in binary code or reflected binary code (Gray code), and can be normalized so as to ensure that only position-relevant bits will be transmitted.
In addition, a parity bit can be optionally evaluated in order to check data integrity. Also, special bits can be transmitted, which are used by some sensors to perform tasks such as signaling error states to the master.
A digital 24 V input can be configured as a latch function in order to retain the encoder value when specific external events occur.
Moreover, two configurable comparators make it easy to quickly detect positions in the PLC program.
In addition to the encoder value, all relevant encoder interface status information is available in the PLC input image table.
|Article name||1 x SSI encoder interface|
|Scope of delivery||1 x SSI encoder interface|
|Dimensions (DxWxH)||110 x 14 x 73 mm|
|Weight||Approx. 75 g|
|Number of SSI decoders||1|
|Supported data bits||13 … 31 bits|
|Parity||None, even, odd|
|Internal Gray-binary conversion||Configurable|
|Encoder value normalization||Configurable|
|Encoder value latch function||Can be triggered with a 24 V digital input|
|Power supplied to encoder by module||24 V DC, 100 mA, fused|
|Diagnoses||Wire break/frame error, 24 V encoder supply, Configuration error|
|External||Max. 20 mA + load on 24 V encoder supply (max. 100 mA)|
|Internal||Max. 130 mA|
|Power dissipation||Max. 1.0 W|
|Input characteristic curve||Type 2, EN 61131-2|
|Rated value||500 mA|
|Leakage current||Max. 0.5 mA|
|Parameter configuration length||10 bytes|
|Ambient temperature||0 °C … +60 °C|
|Transport and storage temperature||-20 °C … +80 °C|
|Relative air humidity||95 % r H without condensation|
|Protection rating||IP 20|
|Surrounding Air Temperature||0 °C … +60°C|
|Noise immunity||DIN EN 61000-6-2 “EMC Immunity”|
|Interference emission||DIN EN 61000-6-4 “EMC Emission”|
|Vibration and shock resistance||DIN EN 60068-2-8:2008 “Vibration”, DIN EN 60068-27:2010 “Shock“|
|TB20, Manual SSI encoder interface||1||8 MB|