Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 22)

2–5 Decoder Features
Publication 2755-833
The HOST port supports RS-232, RS-422, and RS-485 (using
Allen-Bradley DH485 protocol) interfaces. The HOST port allows
the exchange of data between the decoder and a host computer or
Allen-Bradley PLC controller.
The NEMA Type 1 decoder uses an IEC 320 power entry connector.
The NEMA Type 4 decoder uses a standard 3-pin connector with a
separate ON/OFF toggle switch (that is sealed to comply with
NEMA Type 4 standards).
Power cord options are available for each decoder and are listed in
the Decoder Options section.
The decoders are designed to retain configuration during short term
power interruptions. Controlled discharge of an on-board capacitor
supports configuration retention for 6 hours at an ambient
temperature of 50
_C (122_F), or 50 hours at 30_C (86_F). The
capacitor accumulates a charge when power is restored.
An optional battery (catalog number 1747-BA) may be used to retain
the configuration without outside power for up to five years. When
the optional battery is used, power interruptions (whether intentional
or resulting from power supply “glitches”) will have no affect on
operating memory.
If the battery is not used, long term power loss (see above) will result
in the loss of the Extended Match Code Table configuration, the
Primary and Extended Match Code Counters, and the text examples
contained in the Host Replacement Rules. Note that the Replacement
Rules themselves will not be lost, but the test examples you have
entered at the bottom of each rule page will be lost.
Storage memory configuration is transferred into operating memory
on restart if power is lost for a period longer than the on-board
capacitor (and, if installed, optional battery) can support. Refer to
Chapter 3 for an explanation of decoder memory architecture.
The decoders support an optional I/O Module Board with eight
positions for output modules. These I/O modules are used to control
external AC or DC devices. Conditions that activate the outputs are
under user control via the configuration screens or host commands.
Host Port
Power Connector and
On/Off Switch
Memory Backup
Discrete I/O Modules