How To Select A Seven-Segment Display Unit; How To Select Parameter "N" Based On Seven-Segment Display Specifications - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition

15.5.1 How to select a seven-segment display unit

When selecting a seven-segment display unit based on its electrical characteristics, refer to the manual
below:
1. Points to be checked for the seven-segment specifications
1) Whether the input voltage and current characteristics of the data input and strobe signal satisfy the output
specifications of the PLC.
- Whether the input signal voltage (Lo) is approximately 1.5 V or less
- Whether the input voltage is from 5V DC to 30V DC
2) Whether the seven-segment display unit has the BCD decoding and latch functions

15.5.2 How to select parameter "n" based on seven-segment display specifications

The value set to the parameter "n" varies depending on the signal logic of the seven-segment display. Select
"n" as described below.
The check column is provided at the bottom of the table. Check a corresponding type of logic (positive or
negative), and utilize it for parameter setting.
1. Role of the parameter "n"
The parameter "n" should be determined according to the data input logic (positive or negative) of the seven-
segment display unit, the logic (positive or negative) of the strobe signal and the number of sets of 4 digits to
be controlled (1 or 2).
2. Checking the output logic of the PLC
Transistor outputs in PLCs are classified into the sink output type and source output type. The table below
shows the specifications for each type.
Logic
Output type
Pull-up
resistor
Output circuit
Because transistor output (sink) is provided, the
output becomes low level (0 V) when the internal
Description
logic is "1 (ON output)".
logic."
Check
→ For the wiring, refer to the Hardware Edition of the used PLC.
Negative logic
Sink output (− common)
Logic 1
Y000
ON
LOW
COM1
This is called "negative
15 External FX I/O Device – FNC 70 to FNC 79
15.5 FNC 74 – SEGL / Seven Segment With Latch
Positive logic
Source output (+ common)
+V0
HIGH
Y000
Pull-
down
resistor
PLC
Because transistor output (source) is provided, the
output becomes high level (V+) when the internal
logic is "1 (ON output)".
logic."
11
12
13
14
15
16
V+
ON
Logic 1
17
PLC
This is called "positive 18
19
20
455