• A safety program is executed at a fixed cycle according to a set safety cycle time. The safety FB that monitors the time must meet the following requirements.

⋅ The timeout processing may be delayed by the safety cycle time by executing the safety program. Set the safety cycle time so the delay by the safety

cycle time does not pose a hazard.

⋅ If the program is executed exceeding the safety cycle processing time, the timeout may be delayed. Ensure that an abnormality does not occur during

operation.

FB details

The FB requires two inputs indicating the guard position for safety guards with two switches (according to ISO14119),

i_dDiscrepancyTime input and i_bReset input. If the safety guard has only one switch, i_bS_GuardSwitch1 and

i_bS_GuardSwitch2 inputs must be the same signal. The monitoring time (i_dDiscrepancyTime) is the maximum time

required for both switches to respond when closing the safety guard.

When opening the safety guard, both i_bS_GuardSwitch1 and i_bS_GuardSwitch2 inputs should switch to OFF.

o_bS_GuardMon output switches to OFF as soon as one of the switches is set to OFF. When closing the safety guard, both

i_bS_GuardSwitch1 and i_bS_GuardSwitch2 inputs should switch to ON. This FB monitors the symmetry of the switching

behavior of both switches. o_bS_GuardMon output remains OFF if only one of the contacts has completed an open/close

process. The behavior of o_bS_GuardMon output depends on the time difference between the switching inputs. The

discrepancy time is monitored as soon as the values of both i_bS_GuardSwitch1/i_bS_GuardSwitch2 inputs differ. If

i_dDiscrepancyTime has elapsed, but the inputs still differ, o_bS_GuardMon output remains OFF. If the second corresponding

i_bS_GuardSwitch1/i_bS_GuardSwitch2 input switches to ON within the value specified for i_dDiscrepancyTime input,

o_bS_GuardMon output is set to ON following acknowledgment. i_bS_StartReset and i_bS_AutoReset inputs shall only be

activated if it is ensured that no hazardous situation can occur when a safety programmable controller is started.

WARNING

• Connect the two signals/switches of a safeguard to i_bS_GuardSwitch1 and i_bS_GuardSwitch2 independently in your application. If you have a single

signal/switch, connect the same signal to both FB variables.

• The time value for the i_dDiscrepancyTime parameter should be determined and validated according to your application and its risk analysis. This variable

should be connected to the 0ms constant if both signal inputs (i_bS_GuardSwitch1 and i_bS_GuardSwitch2) are connected to the same signal in your

application.

4 SAFETY FB SPECIFICATIONS

4.8 M+SF_GMON_R

Table of Contents