Mitsubishi Electric MELSEC iQ-RJ71GF11-T2 - Safety Data Holding Time When System Switching Occurs

372
APPX
Appendix 7 Processing Time
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.
*1
*1 The variables in the equation have the following meaning.
*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
H
) may be calculated by the following formula.
2.5 + (2  LS) + Tsw + Tso + TMmst
Pattern No. System switching cause Safety data holding time (S
H
) [ms] Timing chart
1 • Failure of the control system power supply module
*3
• Power-off of the control system
• Failure of the control system SIL2 Process CPU
• Failure of the control system base unit
*4
• Failure of the control system redundant function
module
*4
Delay time until detection of the system switching
cause
*2
+ Tsw + Tso + TMmst
Page 373 Pattern 1
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
Delay time until detection of the system switching
cause
*2
+ Tsw + Tso + TMmst
Page 373 Pattern 2
3 System switching request
from the RJ71GF11-T2
(own station)
Own station data link
error
310 + (3  Ls) + Tc + Tsw + Tso + TMmst + SS Page 374 Pattern 3
4 Communication error with
the system switching
monitoring target station
210+Tc+Tsw+Tso+TMmst+SS Page 375 Pattern 4
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)