Safety Data Holding Time When System Switching Occurs - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Safety data holding time when system switching occurs

This section describes safety data holding time when system switching occurs in a system using the SIL2 Process CPU.
Redundant master station
The following are the formulas to calculate safety data holding time when system switching occurs in the redundant master
station configuration.
Pattern No. System switching cause
1 • Failure of the control system power supply module
• Power-off of the control system
• Failure of the control system SIL2 Process CPU
• Failure of the control system base unit
• Failure of the control system redundant function
module
2 • Stop error of the control system SIL2 Process CPU
• Execution of the system switching instruction
• System switching request from the engineering tool
• System switching request from another network
module
3 System switching request
from the RJ71GF11-T2
(own station)
4
*1 The variables in the equation have the following meaning.
Variable Meaning
Tsw SIL2 Process CPU system switching time [ms] ( MELSEC iQ-R CPU Module User's Manual (Application))
Tso Delay time until initial safety output after system switching ( MELSEC iQ-R CPU Module User's Manual (Application))
TMmst Transmission interval monitoring time of the master station (safety station) [ms] ( Page 348 Transmission interval monitoring time)
SS SIL2 Process CPU sequence scan time [ms] ( MELSEC iQ-R CPU Module User's Manual (Application))
Tc System switching monitoring time setting value [ms] ( Page 139 Supplementary Cyclic Settings)
LS Link scan time [ms] ( Page 341 Link scan time)
*2 For delay time until detection of the system switching cause, refer to the following.
 MELSEC iQ-R CPU Module User's Manual (Application)
*3 Depending on the failure status of the power supply module, the calculation formula of the safety data holding time (SH) may be as
follows.
500+Tsw+Tso+TMmst
*4 When the redundant function module is disconnected from the base unit or depending on the failure status of the base unit, the safety
data holding time (S
2.5 + (2  LS) + Tsw + Tso + TMmst
APPX
372
Appendix 7 Processing Time
*1
*4
Own station data link
error
Communication error with
the system switching
monitoring target station
) may be calculated by the following formula.
H
Safety data holding time (S
*3
Delay time until detection of the system switching
*2
cause + Tsw + Tso + TMmst
*4
Delay time until detection of the system switching
*2
cause + Tsw + Tso + TMmst
310 + (3  Ls) + Tc + Tsw + Tso + TMmst + SS
210+Tc+Tsw+Tso+TMmst+SS
) [ms] Timing chart
H
Page 373 Pattern 1
Page 373 Pattern 2
Page 374 Pattern 3
Page 375 Pattern 4