9 - 11

MELSEC-F
WHEN COMMUNICATING DATA USING THE MC PROTOCOL9

9 - 11

9.1.4 Character area transmission data

This section explains how to transmit the bit device data and word device data

handled in the character areas, as well as the order of transmission when

communicating data between an external device and the PLC by each command.

The transmission data shown in the examples is contained in character area B when

reading, and in character area C when writing, testing.

(1) Data communication using ASCII code

(a) When reading to or writing from a bit device memory

The bit device memory can be read and written in bit units (one device point)

or word units (16 device points).

How data is transmitted in each case is explained below.

1) Bit units (one point)

In case of bit units, the bit device memory is handled from the designated

head device for the number of designated device points sequentially from

the left. They are expressed as "1" (31H) if the device is on or "0" (30H) if

the device is off.

(Example)

Indicating the ON/OFF status of five points from M10

2) Word units (16 points)

When the bit device memory is handled as word units, each word is

expressed in hexadecimal values in 4-bit units sequentially from the

higher bit.

(Example)

Indicating the ON/OFF status of 32 points from M16

Indicates that M14 is ONIndicates that M13 is OFFIndicates that M12 is ONIndicates that M11 is OFFIndicates that M10 is ON
0
30H
0
30H
A
41H
0
30H
5
35H
1
31H
0
30H
1
31H
0
30H
1
31H
0
30H
0
30H
0
30H
0
30H
44H
D
34H
4
LLHH
2
32H
0
30H
0
30H
Head device Device
point Data
0
30H
0
30H
A
41H
B
42H
1
31H
2
32H
3
33H
4
34H
C
43H
D
44H
1
31H
0
30H
0
30H
2
32H
B15

10101011000100100011

B14B13B12 B11B1 0B9 B8 B7 B6 B5 B4 B3 B2 B1B0

010011001101

B15B14B13 B12 B11B10B 9 B8 B7B6 B5 B4 B3 B2 B1 B0

AB123 4CD

3130 29 28 27 26 25 24 23 22 21 20 19 18 17 16 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32
30H
0
30H
0
32H
2
44H
D
34H
4
LH
0
30H
0
30H
0
30H
Head device Device
point Data Data
The device point is "02" in 16-point units.1: Indicates ON0: Indicates OFF
MMMMMM MM MM MM MM MM MMMMMMMM MM MM MM MM