SSI Encoder Interface
PN 750-630, 750-630/000-001, 750-630/000-006
Technical Description:
This technical description is only valid for hardware and software versions
X X X X 2 B 0 2----. The product series number is printed on the right side of the module.
The operational mode of the module is factory preset to discern a 24 bit absolute encoder Graycode signal transmitted at 125kHz.
The following description is preliminary and is applicable to the factory configuration.
Attention:
The lowest power jumper contact is not carried out for some modules (e.g. 4-channel)! A module which needs all contacts (e.g. 2 channel digital) may not be connected to the right hand side of modules which do not have 3 power jumper contacts (e.g. 4 channel modules).
The SSI Interface is able to run with all WAGOÇI/OÇSYSTEM bus-couplers (except for the economy type).
Input |
Type |
Function |
Signal D+ and Signal D- |
Input, RS422 |
Positional data from encoder, Graycode. |
Signal Cl+ and Signal CL- |
Output, RS422 |
Clock signal output for communications interface. |
+24 V DC |
Input |
24 V DC supply voltage to module, field connection. |
0 V DC |
Input |
0 V DC supply voltage return to module, field |
|
|
connection. |
The use of this module in conjunction with a SSI encoder provides direct positional information rather than the type of data resultant from incremental type encoders. Absolute encoders are comprised of several data disks which generate a data
word which is unique through out the 360 degrees of rotation. The data format is a modified binary pattern in either Graycode or Dualcode.
The resolution of the sensor depends upon the configuration of the sensor and the physical number of revolutions in the motion profile. Since the basis of the encoder is to provide absolute positional information based upon a mechanical configuration limited to one revolution or less. The maximum resolution of this module is 24 bit.
The frequency of the data signal input to the SSI module is maintained at 125 kHz. Listed below are the recommended cable lengths for the various clock signal Baud rates.
Baud rate
100 kHz
200 kHz
300 kHz
400 kHz
Maximum cable length
400 meters
200 meters
100 meters
50 meters
Organization of the inand output data for ModBus
The module is seen like an analog input with 2 x 16 Bit input data.
Inputs:
Word |
Data Word Designation |
|
D0 |
(Bit 0-15) |
Positional data, |
Positional data, |
|
|
Input byte 1 |
Input byte 0 |
D1 |
(Bit 16-31) |
Positional data, |
Positional data, |
|
|
Input byte 3 |
Input byte 2 |
