Fagor SVA Series, Manual

Page: 10 / 16

Page 10/16 - "SVA" - V1209
PARAMETERS FOR SSI PROTOCOL IN "SVA" LINEAR ENCODERS
Resolution: (Default value = 0.1
μ
m)
Options: 0.1
μ
m, 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 measuring
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 transmit-
ted until the next clock pulses are received.
3: Timed calculation: The value is calculated a specified time after the first clock pulse is received.
The time period is introduced in
μ
s.
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.