GE Industrial Solutions Entellisys 5.0 User Manual - Manual (Page 24)

System architecture 24
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1.3.11 Discrete I/O
The discrete 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 discrete 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 discrete 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 discrete I/O, see Discrete I/O on page 167 .
1.3.11.1 Discrete I/O cards
The input and output signals from the CPU are transferred through the discrete 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.
1.3.11.2 Discrete I/O cable
This cable connects the discrete I/O card to the terminal block. Each cable transmits 64 I/O
points.
1.3.11.3 Terminal block
The terminal block accepts 64 I/O signals from the discrete I/O card through a single cable and
breaks out the individual signals into 64 terminals for wiring.
1.3.11.4 “OR” boards
These boards are only required for redundant discrete 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.
1.3.11.5 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 discrete I/O points may have
relays left off.
1.3.11.6 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.