Mitsubishi Electric MELSEC FX3U Programming Manual page 206

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
5. Differences in the operation caused by auxiliary relay (M) numbers
When an auxiliary relay (M) is specified as a device in LDP, LDF, ANDP, ANDF, ORP and ORF instructions,
the operation varies depending on the device number range as shown in the figure below.
<M0 to M2799, M3072 to M7679>
[1]
M0
X000
[2]
M0
[3]
M0
[4]
M0
<M2800 to M3071>
M2800
SET
M2800
SET
X000
M2800
SET
M2800
SET
M2800
SET
M2800
SET
M2800
SET
M2800
204
SET M50
M0
SET M51
SET M52
M53
M0
Block A
M1
M2800
M2
M3
Block B
M4
M5
M6
Block C
M7
After M0 is driven by X000, all contacts [1] to [4] corresponding
to M0 are activated.
•The contacts [1] to [3] detect the rising edge of M0.
•Because of LD instruction, the contact [4] is conductive
while M0 is ON.
From M2800 driven by X000, the program is divided into the
upper block (block A) and the lower block (block B). In each of
the blocks A and B, only the first contact which detects the
rising or falling edge is activated.
Because of LD instruction, the contact in the block C is
conductive while M2800 is ON.
By utilizing these characteristics, "transition of state by same
signal" in a step ladder circuit can be efficiently programmed.
7 Basic Instruction
7.5 LDP, LDF, ANDP, ANDF, ORP, ORF