Special Diagnostic Auxiliary Relays; Special Single Operation Pulse Relays - Mitsubishi FX1S Series Programming Manual

FX Series Programmable Controllers
4.3.3

Special Diagnostic Auxiliary Relays

A PLC has a number of special auxiliary relays. These relays all have specific functions and
are classified into the following two types.
a) Using contacts of special auxiliary relays
- Coils are driven automatically by the PLC. Only the contacts of these coils may be
used by a user defined program.
Examples: M8000: RUN monitor (ON during run)
b) Driving coils of special auxiliary relays
- A PLC executes a predetermined specific operation when these coils are driven by the
user.
Examples: M8033: All output statuses are retained when PLC operation is stopped
Available devices:
• Not all PLC's share the same range, quantity or operational meaning of diagnostic
auxiliary relays. Please check the availability and function before using any device.
PLC specific diagnostic ranges and meanings are available in chapter 6.
4.3.4

Special Single Operation Pulse Relays

When used with the pulse contacts LDP, LDF, etc., M devices in the range M2800 to M3072
have a special meaning. With these devices, only the next pulse contact instruction after the
device coil is activated.
1
LDP
LDP
3
LDP
4
LD
Turning ON X0 causes M0 to turn ON.
• Contacts , ‚ and ƒ are pulse con-
tacts and activate for 1 scan.
• Contact „ is a normal LD contact and
activates while M0 is ON.
M8002: Initial pulse (Turned ON momentarily when PLC starts)
M8012: 100 msec clock pulse
M8034: All outputs are disabled
M8039: The PLC operates under constant scan mode
M0 to M2799
M0
SET
X0
M0
SET
M0
2
SET
M0
SET
M2800
M50
5
X0
M0
LDP
M2800
M51
6
M2800
M52
LDP
M2800
7
M53
LDP
8
LD
Turning ON X0 causes M2800 to turn ON.
• Contact † is a pulse contact and acti-
vates for 1 scan.
• Contacts … and ‡ are pulse contacts
of the same M device as contact †.
Contact † has already operated, so
contact … and ‡ do not operate.
• Contact ˆ is a normal LD contact and
activates while M2800 is ON.
FX FX
1S 1N
M2800 to M3072
SET M50
M2800
SET M51
SET M52
SET M53
Devices in Detail 4
FX FX
2N 2NC
4-5