Fagor GA Manual Del Usario página 10

PARAMETERS FOR SSI PROTOCOL IN "GA" LINEAR ENCODERS
Resolution: (Default value = 0.1μm)
Options: 0.1μm, 1 µm and 10 µm
Number of bits: (Default = 32)
This parameter can only be set to an even value and it is recommended that it only be used as
such. If the system that is going to read the encoder works with a defined odd number of bits
then it is necessary to do the following:
- Add one bit to make the number to even. 23 + 1 = 24
- Select "Transmit the last bit as 0" .
- Adjust the time out to a desirable value
By doing this the transmission will end with the time out condition because the pulses given by
the master are less than needed by the encoder
The appropriate data length depends on the resolution of the encoder and the encoders mea-
suring length.
Data code: (Default = Binary)
0 = binary, 1 = gray
Transmit the last bit as 0: (Default = 0)
When set to "1" the data output is shifted to the left and the LSB is set to 0 to adjust the data
output to an odd number of pulses. See also "Number of bits"
Parity Bit: (Default = NO)
If parity option is specified the parity bit is sent after the LSB. It must be set to odd or even to
comply with subsequent electronics.
Latch: (Default = continuous)
Three options exist:
1: Calculate continuously: The value is calculated continuously and upon receipt of clock pulses
the last value calculated is sent.
2: Calculate once: The value is calculated on receipt of the last clock pulse. This value is not
transmitted until the next clock pulses are received.
3: Timed calculation: The value is calculated a specified time after the first clock pulse is re-
ceived. The time period is introduced in μs.
SSI time out
This is the time out value in microseconds. It sets the period of time before a reset will occur
should all data bits not be received during a transmission. The time out value defines the lowest
communication frequency, i.e. maximum time from the beginning to the end of the transmission.
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