5
5-6 Genius Modular Redundancy Flexible Triple Modular Redundant (TMR) System
User’s Manual –March 1995 GFK-0787B
Single Input Sensor to Triplex Block Group
Field
Switch
Zener
Diode
Power feed outputs require isolation diode when single input device is
wired to more than one block.
Operation of the Input Autotest
The following actions are performed during the Input Autotest:
the power feed outputs * are pulsed Off. Selected input channels are pulsed On.
all associate d inputs are checke d for th eir ability t o detect the O n or Of f state, as
appropriate, and a fault is reported if th e correct state is not det ected..
While it is being tested, a block continues to supply its last valid set of inputs instead of the
physical inputs to the PLCs.
Test Verification
By allowing some inputs to be turned On, the Input Autotest checks its own operation.
The following table shows cycles in which blocks are autotested, and circuits that are
turned On in the same cycle
Block
Type 1st A/T
Cycle 2nd A/T
Cycle 3rd A/T
Cycle 4th A/T
Cycle Circuits Turned
On at the Same
Time
Circuit Fa il
Mask
16 Cir-
cuit DC Block A
Block B
Block C
Block C
Block A
Block B
Block B
Block C
Block A
Block A
Block B
Block C
1,3,5,7,10,12,14
2,4,6,8
9,11,13,15
2A55
00AA
5500
32 Cir-
cuit DC Block A
Block B
Block C Block A
Block B
Block C
Block C
Block A
Block B
Block B
Block C
Block A
1,5,9,13,17,21,25,29
2,6,10,14,18,22,26,30
3,7,11,15,19,23,27,31
4,8,12,20,24,28,32
1111 1111
2222 2222
4444 4444
8888 0888
Notes: Bit 16 corresponds to the power feed output. It is always 0.
For 16-Circuit blocks, each circuit is turned On each cycle when looked at across all
3 blocks, but the same circuit is never turned On at more than one block at a time.
For 32 Circuit blocks, almost all circuits are turned On each cycle when looked at
across all 3 blocks, but the same circuit is never turne d On at more th an one block
at a time.
*also see chapter 8 for installation and wiring information.