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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 module (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.

Application example

Safety Programmable Controller Application example

Safety Programmable Controller Installation example

An application example of the Safety Programmable Controller
at real facilities is introduced in an easy-to-see video movie.
It also contains audio explanations
(8 minutes and 7 seconds in FLV mode).