6 ssi, Ssi overview, Ssi -67 – Delta RMC101 User Manual
Page 611: Ssi overview -67, 1 ssi overview
SSI 6.6
Transducer Interface Modules
6-67
Each revolution of the resolver generates 65536 counts. To calculate the Scale parameter,
determine how many position units there are in one turn of the resolver.
The sign of the Scale is positive if the counts and the position units increase and decrease
together. The sign is negative if the counts and position units move in opposite directions.
You can use the Resolver Calibration Tool to assist with this step. To access it, on the Tools
menu, click Resolver Calibration Tool.
2. Select the Coordinate Limit
In most cases, the Coordinate Limit can be set to -32768 (for a positive scale) or 32767 (for a
negative scale). This will allow position units to go from -32768 to 32767, which is the same
range as most PLCs use for 16-bit numbers.
You can pick other values for the coordinate limit if you wish to specify a different range of valid
position units.
You can use the Resolver Calibration Tool to assist with this step. To access it, on the Tools
menu, click Resolver Calibration Tool.
3. Set the Count Offset
Move the axis to a known position and issue a Z command with the current desired position for
the Command Value. This will change the Count Offset parameter such that the Actual Position
will indicate the current position.
The Count Offset value must be stored in non-volatile memory in order to read the correct
position the next time the RMC powers up. Use the Update Flash command to store the
parameters to non-volatile memory.
See also:
Resolver Overview
Resolver Configuration
Resolver LED Indicators
Resolver Wiring
Resolver Specifications
6.6 SSI
6.6.1 SSI Overview
Synchronous Serial Interface (SSI) is a widely accepted controller interface. Position data from
the sensor is encoded in a binary or Gray Code format and transmitted over a high-speed
synchronous interface.
SSI transducers and absolute encoders offer the following advantages:
• High resolution. Up to 2 µm (approx. 0.00008")
• Noise immunity
• Cost effective data transfer (only one 6-wire cable is needed)