Error Messages; Oversampling Option - gefran MK4 Series Installation Manual

The SSI output goes to 0 if the echo is absent (magnet out of measurement range or internal device error).
The position of the magnet on the sensor is defined by the magnetostrictive technology. Internal position sampling can vary
from 2 kHz to 500 Hz depending on the stroke.
The displacement signal is supplied in binary or Gray code and transmitted to the controller via SSI.
Normally, when data are available, they are transmitted to the SSI shift register, where they are available to the controller.
Therefore, the shift register refresh rate is equal to the internal interrogation rate.
In the version with "oversampling," the transducer control electronics is synchronised with the SSI clock trains and provides
an output before each interrogation.
The supplied data are calculated via a first-order interpolation and are equal to:
The data is supplied to the shift regi-
ster considering possible Jitter in the
controller interrogation time (40 mSec
is currently considered).
Lower Jitter levels ensure better inter-
polation results (see Figure 10).
To maintain synchronism between
SSI clock and shift register refresh,
the interrogation rate can vary from a
maximum of 5.5 KHz to a minimum of
125 Hz.
Typical value considered = 4KHz.
6

ErrOr MESSaGES

OVErSaMPlING OPTION

Out = M + V * T
M = last internal measurement
V = magnet speed
T = time elapsed since last measurement
NOrMal OPEraTION
Internal Measure
Data on Out
Security time = 40 µS + 10 µS
MaX ErrOr IN CaSE OF
JITTEr IN SaMPlING TIME
CaSE 1: Decreasing of sampling time
from 270 to 230
CaSE 2: Increasing of sampling time
from 230 to 270
Security time = 50 µS (compensated)
Data Ready SSI Sample Time
250 µS sampling time
Security time = 50 µS (compensated)
270 µS sampling time
The system doesn't less the sample
The error in position is = V*40 µSes
Security time = 50 µS (compensated)
230 µS sampling time
The error in position is = V*40 µSes
Fig. 10
85190A_MAN_Installazione_MK4-IK4/SK4_11-2012_ENG
10 µS
230 µS sampling time
90 µS
270 µS sampling time