Tecomat TC600
TXV 138 08.02
82
T
signal period time at BM input DI0
t
F
phase shift of signals at BM inputs DI1 and DI0
Control of the measurement mode is done by a program using the image
of the binary output DO0 of BM (by image Yn.0).
If the bit Yn.0 = 0, measurement of the signal period is performed at in-
put DI0 of BM, if the bit Yn.0 = 1, measurement of the phase shift of signals
between inputs DI1 and DI0 of BM is performed.
Physical output DO0 of BM can be used only for indication of the func-
tion mode.
In signal period (frequency) measurement, it is possible to measure the
signal within the frequency of about 1 Hz to 1 kHz. The measured number of
cycles of the clock signal then reaches values of 32767 to 33. The value
65535 signals exceeding of the measurement range (it corresponds with the
input signal frequency lower than 1 Hz, or possibly with a non-connected in-
put).
For conversion of the number of cycles of the internal clock signal to the
time information, the following relationship holds:
T [µs] = n x 30.5175
T
signal period time at input DI0 of BM
n
contents of two bytes of the scratchpad determined by the parame-
ter
Xn
of directive
#unit
In the case of measurement of a sine alternating signal period,
doubling of frequency occurs at the input circuits (two-directional rec-
tifying) and the measured period value corresponds with the half of its
real value at input DI0 of BM.
#program period
;
#unit 0, 0, Digit_600, 2, 2, X0, Y0, On ;binary inputs
#unit 0, 0, Period_600, X2, X_On
;period meter
;
#def Time XW2
;signal period in clock
cycles
#def cons1 30.5175
;const. of conversion cycles -> µs
#def cons2 0.000001
;const. of conversion µs -> s
;
#reg float Period,
;signal period in µs
Frequency
;signal frequency in Hz
;
P 0
LD
0
WR
Y0.0
;period measurement
;
LD
Time
UWF
MUF
cons1
WR
Period
;period in µs
;
Graphic illustration of
time of the period and
phase shift
Measurement mode
control
Period measurement
Example of the period
rectification
