3.1.1 Sampling Time
The fast position value sampling time is based on the transmission of a SYNC edge in a
protocol package (where the SYNC edge can be user-commanded or belong to an
EXTRA package, see above).
The duration from SYNC edge to sampling time point is based on the following formula:
t
sample
= t
latency
+ t
delay
± t
jitter
where
t
latency
< 100 ns
t
delay
= 5 ns/m * l_cable [m]
t
jitter
= 6.5 ns + 13.33 ns * EDGES
EDGES refers to the number of set bits in the EDGES register, see chapter 6.3.7. Sam‐
pling latency will always be less than 1 μs. Note that position values will only be avail‐
able after a longer duration (around 10 μs after SYNC edge) due to data serialization
and transmission to the drive controller.
3.2 Safe Channel 1
The safe position value of the motor feedback system is transferred on the Safe Chan‐
nel as an absolute value. In addition, the status of the encoder is reported on this chan‐
nel in the form of errors and warnings.
NOTE
The safe position value transferred on the Safe Channel is not synchronous with the fre‐
quency inverter cycle signal at the SYNC input.
The safe position is used by the DSL Master IP Core to check the fast position value of
the process data channel and can be used by the frequency inverter application for the
same purpose.
Where there are deviations between the safe and the fast position values, an error
message is generated (see chapter 5.4.2). In this case, the protocol replaces the fast
position with the estimated position. Please see chapter 7.3.1 for details.
In each package of the safe channel, a collection of status bits is transferred that
reflects the error and warning condition of the motor feedback system.
NOTE
It should be noted that each bit of the summary byte of the Safe Channel refers to one
status byte the motor feedback system. Each status byte of the encoder can be read
with a "short message" (see chapter 7.5.1).
3.2.1 Sampling Time
The safe position value (both channel 1 and 2) is not synchronous to the drive con‐
troller cycle signal at the SYNC input. The safe position value is transmitted in eight
protocol packages. The sampling point of the safe position is based upon the SYNC
edge of the first of these eight protocol packages (keeping in mind that the SYNC edge
might be user-commanded or belong to a DSL Master-generated EXTRA package, see
above). Depending on the actual position of the last user-generated SYNC edge the safe
position value will be 1 to 9 protocol packages old. Depending on the timer settings for
SYNC to EXTRA packages the sampling time of the safe position value will change
between measurements.
3 PROTOCOL OVERVIEW
12
T E C H N I C A L I N F O R M A T I O N | HIPERFACE DSL
®
8017595/ZTW6/2018-01-15 | SICK
Subject to change without notice
To Next Page
Loading...
