11
Common I/O Module Functionality
11.1
BPPx Processor
The BPPx processor board is used with most Ethernet-based I/O modules. It contains the following:
•
High-speed processor with RAM and flash memory
•
Two fully independent 10/100 Ethernet ports with connectors
•
Hardware watchdog timer and reset circuit
•
Internal temperature sensor
•
Status-indication LEDs
•
Electronic ID and the ability to read IDs on other boards
•
Input power connector with soft start and current limiter
•
Local power supplies
The processor board connects to an acquisition board specific to the I/O module function. When input power is applied, the
soft-start circuit ramps up the voltage available on the processor board. The local power supplies are sequenced on, and the
processor reset is removed. The processor completes self-test routines, and then loads application code specific to the I/O
module type from flash memory.
The processor reads board ID information to ensure the correct matching of firmware, acquisition board, and terminal board.
With a good match, the processor attempts to establish Ethernet communications, starting with request of a network address.
The address request uses the industry standard dynamic host configuration protocol (DHCP) and the unique identification
read from the acquisition and terminal boards. After Ethernet initialization, the processor programs the on-board logic, runs
the application, and enables the acquisition board to begin operation. This network redundancy function is more tolerant of
faults than a classic Hot Backup where the second port is only used after a primary port failure.
The processor application code contains all the logic necessary to allow the I/O module to operate from one or two Ethernet
inputs. When operated from two Ethernet inputs, both network paths are active all the time. A failure of either network will
not result in any disturbance to the I/O module operation, and the failure is indicated through the working network
connection. The Ethernet ports on the processor auto-negotiate between 10 and 100 Mbps speed, and between half-duplex and
full-duplex operation.
11.1.1
Power Management
The processor includes power management of its 28 V input circuit. The management function provides soft start to control
current inrush during power application. After applying power, the circuit provides a fast current limit function to prevent a
failure from propagating back onto the 28 V power system. When power is present and working properly, the green PWR
LED is lit. If the current limit function operates, the PWR LED will be out until the problem is cleared.
11.1.2
ID Line
The processor board and acquisition board(s) within the I/O pack contain electronic ID parts that are read during power
initialization. A similar part located with each terminal board pin connector allows the processor to confirm correct matching
of I/O pack to terminal board and report board revision status to the controller.
Common I/O Module Functionality
GEH-6855_Vol_II System Guide 441
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