User manual - MODULE SIN-8
5.
PRINCIPLE OF OPERATION
After power on device signalizes its operation by continuous flashing of green LED
marked (RUN). Short flash of red LED (Tx/MASTER) means that some data is being
transmitted via RS-485 interface.
Green LEDs marked IN1 - IN8 signalize active state on particular binary inputs (logic HIGH
state). When particular input is in active state then corresponding register value is 01h,
otherwise its value is 00h. Register 09h contains information of all inputs compacted into
single byte, where particular bits are related to particular inputs (see
THE MODBUS
PROTOCOL HANDLING
).
a)
b)
Figure 5.1. The traces of signals:
a) without contacts oscillations, b) with contacts oscillations
Actualisation of registers state occurs only if input signal have fulfil some time restrictions
(see Figure 5.1). These restrictions depend on settings of internal digital filter implemented in
firmware. Filter allows to eliminate signal oscillations corresponding to contacts bouncing (of
mechanical sensors). Filter is factory switched off. To ensure proper working (it means that
module do not omit any pulse) while filter is on duration of LOW (t
0
) and HIGH (t
1
) states must
be not shorter than
F
×
50
s
, where F means filter setting. While filter is „off” then t
0
and
t
1
must be not shorter than 125
µ
s.
See the table below (Tab. 5.1) to check proper periods for
all frequencies.
7
t0
t1
t0
t1
oscillations
Summary of Contents for SIN-8
Page 11: ...User manual MODULE SIN 8 11 ...
