GE GFK-0787B user manual Triplex bit is optional the need for this bit depends on

7

<< RUNG 12 >>
IORESIP	IORES

ÐÐ# ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÈÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐ(R)ÐÐÐ

In rung 12, the transition of IORESIP (I/O Reset in Progress) to the Off

state indicates that the requested I/O fault reset has been completed.

This rung resets command bit IORES (I/O Reset) to the Off state.

<< RUNG 13 >>
LOGONFT	FORCLOG

ÐÐ# ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÈÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐ(R)ÐÐÐ

	In rung 13, the transition of LOGONFT (Logon Fault) to the Off state
	indicates that the requested I/O fault reset has been completed. This
	rung resets command bit FORCLOG (Force Logon) to the Off state.
<< RUNG 14 >>
DUPLEX	LOGONFT	FORCLOG

ÐÐ ÐÐÐÐÐ		ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÈÐÐÐÐÐÐÐÐ(S)ÐÐÐ
TRIPLEX		IORES
ÐÐ ÐÐÐ		ÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÐÈÐÐÐÐÐ(S)ÐÐÐ
	In rung 14, if the GMR system is in DUPLEX mode (two CPUs are on
	line) and a logon fault occurs at an output block, LOGONFT turns on.
This turns on the Force Login (FRCLOG) control bit, which forces the
	output block to accept outputs from the newly-online CPU, even if the
output states do not agree with the present voted outputs at the
	output block. This logic also turns on the control bit IORES (I/O Reset).
	IORES is required to clear the Logon Fault status bit (LOGONFT). This
	last action also clears the fault tables in all running PLCs.
	The TRIPLEX bit is optional; the need for this bit depends on the
	application. If used, it provides the same type of PLC logon control
when a third PLC comes on line.
±END:

Caution

Depending on the application, you may prefer to use only the DUPLEX logic shown above to turn on the FORCLOG (Force Logon) command bit. The purpose of PLC logon control is to prevent a CPU that is coming online from changing the state of a critical voted output. Automatic PLC logon is sensible with the DUPLEX status bit, because it ensures that at least two PLCs are driving output information before outputs that disagree with the voted outputs are used when a system is initially powered up. The third PLC coming online has the ability to change an output state if the first two PLCs are already online and already disagree. Because of this, it may not be suitable to ªautomaticallyº log on the third PLC.

GFK-0787B Chapter 7 Programming Information 7-19