GE Mark VIe System Manual page 87

3.3.1 UDH Communicator in a Redundant Controller Set
In dual or TMR Mark VIe controller sets, a single controller is designated to transmit real-time and alarm data for the set; this
is the UDH Communicator. This data includes both control signals (EGD) and alarms (SDI). Since each controller has an
independent, physical connection to the UDH, if a UDH network fault occurs where one controller becomes isolated from its
companion controllers, the isolated controllers assumes the role of UDH communicator for that network fragment. For this
reason, a controller set has only one
designated controller is always a UDH communicator.
Note UDH command data is replicated to redundant controllers by the UDH Communicator, allowing for synchronization
across the redundant controller set.
When a controller does not receive external EGD data from its UDH connection, it may request that the data be forwarded
across the IONet from another UDH communicator. One or more communicators supply the data, and the requesting
controller uses the last data set received. Only the external EGD data used in sequencing by the controllers is forwarded in
this manner.
3.3.2 UDH Network Specifications
Item
Type of Network
Media and Distance
Number of Nodes
Type of Nodes Supported
Protocol
Message Integrity
Time Sync. Methods
3.3.3 Control System Devices on the UDH
3.3.3.1 Mark VIe Controllers
The Mark VIe controllers are applied in a wide variety of industrial control applications. The Mark VIeS Safety controller is
used for safety-critical SIL applications. The Mark VIe UCPA platform is a lower cost, smaller footprint controller with
integral I/O and limited expansion I/O capability. The same ToolboxST application is used for configuration of the Mark VIe
controller product line. For more information, refer to Mark VIe and Mark VIeS Control Systems Volume II: System Guide for
General-purpose Applications (GEH-6721_Vol_II), the chapter Controllers.
The EX2100e excitation controller supplies dc power to the field of the synchronous generator, and controls the generator ac
terminal voltage and/or the reactive volt-amperes by means of the field current. The excitation control system is supplied in
NEMA 1 freestanding floor-mounted indoor type metal cabinets. The cabinet lineup consists of several cabinets bolted
together.
Note Refer to EX2100e Excitation Control User Guide (GEH-6781) for further details.
Ethernet Networks
designated controller, while there could be multiple UDH communicators. The
Description
Ethernet, full duplex, in a single or redundant star configuration
Ethernet 100Base-TX for switch to controller/device connections. The cable is 22 to 26 AWG
unshielded twisted pair; category 5e EIA/TIA 568 A/B. Distance is up to 100 m. Ethernet
100Base-FX with fiber-optic cable optional for distances up to 2 km (1.24 mi).
At least 25 nodes, given a 25 Hz data rate. Other configurations may be available.
Controllers, PLCs, operator interfaces, and engineering workstations
EGD, based on UDP/IP
32-bit CRC appended to each Ethernet packet plus integrity checks built into UDP and EGD
Network time protocol (NTP), accuracy ±1 ms.
Public Information
GEH-6721_Vol_I_BP System Guide 87