Fema S40-C1, User Manual, Page: 6 / 28

FEMA ELECTRÓNICA . Series S . S40-C1
6
Special working mode for applications with low frequency signals.
Applies to ratemeter (‘ rt.6 ’), ratemeter quadrature (‘ rtq.7 ’) and peri -
odmeter (‘ Prd.8 ’). The ‘ SLOW ’ mode allows to measure slow fre -
quencies down to 1 mHz (0,001 Hz) and is functional up to 200 Hz.
The ‘
SLOW ’ mode provides the fastest response time possible for a
given application, calculating the frequency and the period based on
the time between consecutive impulses.
The ‘
SLOW ’ mode needs to define the parameter ‘ maximum waiting
time ’ to a value between 1 and 1000 seconds. If this time expires
without a single impulse being received, the reading jumps to ‘0’
(both for ratemeter and periodmeter modes). The ‘ GATE ’ parameter
is not used if ‘ SLOW ’ mode is active.
In ‘ ratemeter quadrature ’ (‘ rtq.7 ’) mode, the activation of the
‘ SLOW ’ mode calculates the frequency based on the time between
consecutive impulses received on channel A, and calculates the
sense of turn (clockwise or counter-clockwise) by comparing each
impulse with the state of channel B. The ‘ edge ’ parameter is fixed to
a ‘ 1--1 ’. Typical application for quadrature frequency measure with
two inductive sensors at low frequency.
1.13 Function ‘Trigger Sense’
Special working mode for counter applications with high frequency
signals, up to 250 KHz. Applies only to the counter mode (‘ cn.1 ’).
The activation of the ‘ FAST ’ mode configures the signal detection by
rising edge. The first edge detected, either rising or falling edge, after
the instrument restart (power-up, or configuration change) is used
for internal initialization and will not be counted as impulse.
1.14 Function ‘cycle counter’ 1.15 ‘SLOW’ mode
The trigger level is automatically configured when selecting a sensor
from the ‘Sensor / Configuration’ (‘ SnSr ’ / ‘ Auto ’) menu list. The trig -
ger level can be also manually modified from the ‘ SnSr ’ / ‘ TrIG ’ menu
entry. The selected value applies to channels ‘A’ and ‘B’ (the reset has
a fixed trigger level at 2.5 Vdc).
At the ‘
SnSr
’ / ‘
TrIG
’ menu, the instrument shows the trigger level
and two vertical leds to the left. These leds inform in real time about
the status (‘0’ or ‘1’) of the input channels ‘A’ and ‘B’. When the led
switches between up and down position, it indicates that impulses
are being detected at the input. If the instrument does not detect
impulses, the led positions remain fixed.
Increase the trigger level pressing key ‘UP’ (
5
) and decrease press -
ing key ‘LE’ (
3
).
Vdc
Time
Trigger level
‘1’
‘0’
Signal detected
channel ‘A’
Status ‘1’
Trigger level
Status ‘0’
Leds of the ‘Trigger
Sense’ function
channel ‘B’
1.16 ‘FAST’ mode
Reading
Time
Setpoint 1
Impulse counter, with ‘reset to preset’
when setpoint 1 is reached
Preset
Time
Cycle counter
0
1
2
3
The counter modes allow to activate a reset function (to ‘0’ or to
‘preset’ value) when an alarm setpoint is reached. With this configu -
ration, the instrument counts in cycles, counting from the instrument
preset value up to the alarm setpoint. Each cycle is counted and ac -
cumulated into an internal memory, accessible through the ‘fast ac -
cess’ menu (key UP (
5
) (see section 1.19.12)) .
To reset the memory of cycles, visualize the value at the ‘uP’ menu,
then press the (
5
) key and the ‘ rSt ’ message appears. Press (
<
) to
reset.