Rockwell Automation T80004 Application Note Field Loop Configuration - Manual (Page 27)

Trusted
TM
AN-T80004 Field Loop Configuration
Issue 10 Jun 13 AN-T80004 27
Digital Outputs
Power Groups
Digital Output module channels are arranged in groups of eight. Forty channel modules therefore have
five groups, thirty two channel modules have four and sixteen channel modules have two.
Each group is isolated from each other, allowing different supply voltages to be used for each group.
Each group has a triplicated switch in the supply line allowing the whole group to be turned off if a fault
cannot be isolated; this is the group failsafe switch (GFSS). The GFSS has a parallel set of three
switches, one controlled by each slice. These are failsafe, so that if a slice is set offline, its switch is
opened. This switch allowed TUV to permit the system to operate indefinitely with one fault, because
there is still a means to shut down the outputs.
‘Top Rail’ is used as the reference point for the channel voltage calculations below, and is about one
‘diode-drop’ below the incoming field supply voltage.
1
8
9
16
17
24
25
32
33
40
Group 1
Group 2
Group 3
Group 4
Group 5
Field Supply
‘Top Rail’
Power to each channel