User`s manual

7-17
7-5 Precautions for operating I/O module
[1] Precautions for operating input module
(1) ON/OFF time of the input signal
In order to ensure ON/OFF condition of the input device correctly (limit switch etc.) on the operation
of the JW300, ON or OFF time should meet the following conditions.
In the input/output process at the beginning of each scanning cycle, ON/OFF state of the logic side
of the input module is written in the data memory and used as input data for operation of the user's
program within its scanning cycle. Therefore, if ON or OFF time of the logic side of the input
module is less than 1 scanning time (Dt), ON/OFF data may not be included in the data memory.
Note: The response time of the input module is made by the electricity charge/discharge characteristics
of the integral circuit of the input module, and it varies depending on the time of duration of ON
or OFF.
Toff shows the difference, shown in the above, between the case when the ON time of the contact
point of the input device is longer as shown by dotted lines and the case when the ON time is
shorter as shown by solid line.
- Calculation example in case the JW-214NA is used as an input module
If 1 scanning time is 5ms,
T
on
> Dt + t
on
= 5 + 0.5 = 5.5 (ms)
T
off
> Dt + t
off
= 5 + 1.5 = 6.5 (ms)
T
OFF
Ton
ton toff
Δ t min. Δ t min.
Contact point of
the input device
Logic side of
the input module
ton toff
toff
Contact point of
the input device
Logic side of the input module
Electricity charge/discharge
characteristics of the integral circuit
Upper limit value of the logic side
100% charge
ON time of the input device (T
ON
)T
on
> Dt + t
on
OFF time of the input device (T
OFF
)T
off
> Dt + t
off
Dt· · · · One scanning time of JW300
t
on
· · · · ·
OFF to ON response time of the input
module
t
off
· · · · ·
ON to OFF response time of the input
module