Rockwell-automation 1772-LP3 PLC - 2/30 Programmable Controller Progra Uživatelský manuál stáhnout pdf (Strana 155)

Output Override and I/O Update Instructions

Chapter 7

713

NOTE: If a fault occurs in a local rack, all racks will behave according to

their last state switch whether dependent or independent mode has been

selected.

Independent fault zone programming is used to zone off independent

sections of user program. The programming for each I/O chassis can be

contained in separate MCR or ZCL zones or more than one I/O chassis can

be contained in a single zone (Figure 7.7). The user may also wish to

enable alternate parts of a program when a fault occurs in a remote I/O

chassis (Figure 7.8).

Independent fault zones are programmed using the appropriate fault status

bits as Examine Off conditions for the MCR or ZCL zones (Figures 7.7

and 7.8). When a fault occurs in a remote I/O chassis, the corresponding

fault status bit is set on. The MCR or ZCL zone conditioned by that fault

status bit will go false, enabling the zone. All outputs within the zone will

be controlled by the zone.

In addition to programming independent fault zones, the user must ensure

that the fault control switch on the S/D panel is set on for independent

mode. Refer to publication no. 1772-929 for the switch locations and

settings of the 1772-SD2 distribution panel.

NOTE: If a fault occurs in a local rack, all racks will behave according to

their last state switch whether dependent or independent mode has been

selected.

7.4.2

Independent Programming

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Rockwell-automation 1772-LP3 PLC - 2/30 Programmable Controller Progra Uživatelský manuál Strana 155