GE Industrial Solutions Entellisys System User Manual - Manual (Page 20)

System architecture 20
1
1.3.10 Digital I/O
The Digital I/O equipment provides programmable input and output logic for customer-specific
requirements.
Examples include the following:
• Sound a horn when a circuit breaker is open
• Trigger an output when voltage exceeds a value
The redundant digital I/O option provides signal processing to/from either CPU. One CPU (the
Master) processes the information and responds. The other provides a backup of the Master
fails. Redundant digital I/O is recommended if any of the signals are critical to the operation of
the system. Critical I/O examples include the following:
• Inputs to automatic throw-over schemes
• Inputs that must trip circuit breaker (such as high transformer pressure)
For more information on Digital I/O, see Digital I/O on page 127 .
1.3.10.1 CPU digital I/O cards
The input and output signals from the CPU are transferred through the CPU digital I/O Cards.
Each card supports 64 bi-directional points that range from 0 to 5 volts. A maximum of two
cards may be inserted for a total of 128 I/O points. The cards come installed in the CPU upon
purchase.
1.3.10.2 Digital I/O cable
This cable connects the CPU digital I/O card to the terminal block. Each cable transmits 64 I/O
points.
1.3.10.3 Terminal block
The terminal block accepts 64 I/O signals from the CPU digital I/O card through a single cable
and breaks out the individual signals into 64 terminals for wiring.
1.3.10.4 “OR” boards
These boards are only required for redundant digital I/O. The output signals from both CPUs
must be “Horde” together, between the terminal blocks and the relay blocks, to prevent
increased voltages from damaging the relays. Each “OR” board supports 16 output signals.
1.3.10.5 Relay blocks
The relay blocks hold solid state input and output relays (16 per block).
Relay blocks are configured as all inputs or all outputs. Unused digital I/O points may have
relays left off.
1.3.10.6 Relays
The input relays transform the customer input (120 Vac or 24-125 Vdc) to 5V inputs for the
Entellisys system.
The output relays are either opened or closed based on programmable logic in the Entellisys
system.