i950 and SSI absolute encoder (rotary/linear): Commissioning steps and important settings
Question;
Commissioning of a load-side SSI-Absolutertgebers im Controller-based system, e.g. i950 as motion axis under a controller with FAST-Motion:
Which procedure is recommended recommended and what is pay pay attention to??
Answer; SSI-Absolutertgeber (rotary / linear): For commissioning commissioning a load-sideabsolute return system with SSI interface (Synchronous Serial Interface) are the following Commissioning steps must be performed:
1. Parameterization of the SSI interface:
0x2C50 SSI Encoder type
0x2C5A:020 SSI Selection Rotary/linear
0x2C52:002 SSI Supply voltage [V]
0x2C5A:001 SSI Transmission rate [kbps]
0x2C5A:022 SSI Monoflop time
0x2C5A:003 SSI Bits/revolution
0x2C5A:002 SSI Telegram length
0x2C5A:xxx Configuration of the in the telegram present data packets for the transmitter position and if applicable existing status and error bits.
2. Kinematics/machine parameters in the motion axis , in particular:
mounting position of engine and position sensor,
Gear ratio,
Feed constant
more...
3. Particularly important: Review of the counting sense of the recorded actual position:
BEFORE the first release the machine should the correct setting of the counting direction of the Check the actual position. If the counting direction is incorrect, positive feedback occurs in the control loop and uncontrolled movements may occur on the machine immediately after the inverter is enabled!
The check can be performed by means of a controlled test movement (open loop) or by moving the machine manually: When moving in a positive direction, the displayed actual position must increase in a positive direction.
Useful information for a better understanding:
SSI monoflop time (0x2C5A;022); The monoflop time is the transmission pause time between two SSI transmissions. Each time the monoflop time elapses, a new position value is recorded and transmitted via SSI.
>SSI telegram length (0x2C5A:002): Only the data bits to be transmitted are counted for the telegram length, excluding the start bit at the beginning of the SSI transmission.
Parameterization of the data present in the telegram: The composition of the telegram is determined by the encoder type used. In addition to the bits for the encoder position, the telegram may also contain status and error bits, see encoder data sheet. The transmitted bits are divided into so-called "data packets" according to their meaning.>Position data
Data packet 1
Data packet 2
Data packet 3
The following settings must be made for the individual data packets that are actually present (not all of them must be present):
Encoding of position data (Gray/binary)
Start bit number (bit position of the least significant bit (LSB) (Counting direction from right to left ascending, starting at 0)
Data packet length (number of bits in the data packet).
