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Safety Programmable Controller

Safety programmable controller MELSEC-QS Series

The safety programmable controller is compliant with international safety standards, EN ISO 13849-1 Category 4/PL e and IEC 61508 SIL 3. It is ideal for medium to large-scale safety control systems. Ladder programs and certified safety function blocks*1 realize flexible programming.

*1. They can be used to structure EN ISO 13849-1 Category 4/PL e and IEC 61508 SIL 3 safety applications.

MELSEC-QS Series system configuration

*2. Number of input points: 8 points (double wiring), No. of output points: 4 points (source + sink type)
*3. Number of input points: 8 points (double wiring)
*4. Number of output points: 4 points (source + sink type)

Reducing costs while increasing diagnostic capabilities and system flexibility

The MELSEC-QS Series solves the complicated wiring and time-consuming troubleshooting issues associated with previous safety relay systems.

Programming with ladder diagrams and safety FBs

■ GX Developer
  • Use GX Developer to start up MELSEC-QS Series safety control systems (programming, monitoring, diagnosis, and debugging). GX Developer can configure CC-Link Safety, CC-Link IE Field Network and safety remote station parameters.*5
*5. GX Works2 is necessary to configure CC-Link IE Field Network settings when using generic programmable controllers.

■ Safety FB (Function Block)*6

Functions that are frequently used for creating safety programs are provided as safety FBs. The safety FBs have been certified.

Safety FB list
FB name Function Description
F+2HAND2 Two hand switch Type II Provides the two-hand control functionality.
F+2HAND3 Two hand switch Type III Provides the two-hand control functionality. (Fixed specified time difference is 500 ms.)
F+EDM External device monitor Controls a safety output and monitors controlled actuators, e.g. subsequent contractors.
F+ENBLSW Enable switch Evaluates the signals of an enable switch with three positions.
F+ESPE Light Curtain (ESPE) Safety-related FB for monitoring electro-sensitive protective equipment (ESPE).
F+ESTOP Emergency Stop Safety-related FB for monitoring an emergency stop switch. This FB can be used for emergency switch off functionality (stop category 0).
F+GLOCK Guard Lock and Interlocking Controls an entrance to a hazardous area via an interlocking guard with guard locking ("four state interlocking").
F+GMON Guard Monitoring Monitors the relevant safety guard. There are two independent input parameters for two switches at the safety guard coupled with a time difference (Monitoring Time) for closing the guard.
F+MODSEL Mode Selector Selects the system operation mode, such as manual, automatic, and semi-automatic, etc.
F+MUTE2 Muting with 2 sensors Muting is the intended suppression of the safety function. (e.g., light barriers) In this FB, parallel muting with two muting sensors is specified.
F+MUTEP Parallel muting Parallel muting with four muting sensors is specified.
F+MUTES Sequential muting Sequential muting with four muting sensors is specified.
F+OUTC Output control Control of a safety output with a signal from the functional application and a safety signal with optional startup inhibits.
F+TSSEN Testable safety sensor Detects, for example, the loss of the sensing unit detection capability, the response time exceeding that specified, and static ON signal in signal-channel sensors systems. It can be used for external testable safety sensors.
F+EQUI Dual input (NC + NC or NO + NO) Converts two equivalent bit inputs (both NO or NC) to one bit with discrepancy time monitoring. This FB output shows the result of the evaluation of both channels.
F+ANTI Dual input (NO + NC) Converts two antivalent*7 bit inputs (NO/NC pair) to one bit output with discrepancy time monitoring. This FB output shows the result of the evaluation of both channels.
*6. The safety FBs are provided for GX Developer version 8.82L or later. (QS001CPU is supported with the first five digits of serial number "11042" or later.)
*7. "Antivalent" means that during normal operation, the two inputs are in opposite states at the same time. This is sometimes called "complementary" or "non-equivalent".

Easy error/failure troubleshooting

■ PLC diagnosis

Safety CPU operating status, current error, operation/error history (including CC-Link Safety system error history) can be checked. Up to 3,000 safety CPU module operations/error histories can be recorded and stored in CSV files.

■ Error details

For safety remote I/O station, error name, date and time of occurrence, error details/troubleshooting are displayed.

Debug functions

Debug functions (device test, write during RUN, etc.) are available in test mode.


Product name Model *
Safety CPU QS001CPU (-K)
Safety main base QS034B (-K)
Safety power supply QS061P-A1 (-K)
QS061P-A2 (-K)
CC-Link IE Field Network master/local (with Safety Communication Functions) QS0J71GF11-T2
CC-Link Safety system master QS0J61BT12 (-K)
CC-Link Safety system remote I/O QS0J65BTB2-12DT (-K)
*: S-mark compatible part models are indicated in parentheses.