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Data Transfer
For a description of operation when the Power switch is
turned on, see reference 190.
.
The cable adapter has 3 major functions:
• Responding to polling.
• Shifting data onto the cable for transmission to the
controller.
• Receiving data from the cable, decoding it for
commands, and/or transferring the data to
read/write storage.
The cable adapter detects the printer address on the
first frame of a transmitted message. The address for a
single online printer is 000. When the Cable Thru
feature is installed, addresses ranging from 000 through
110 are set by the customer. When the address is
received, recognized, and a response is returned, polling
is complete. An address of 111 is invalid.
Data to be transmitted to the controller is moved from
read /write storage, through a serializer / deserializer
(serdes) register, and onto the cable under control of the
cable adapter.
Data that is received is moved into the serdes register
until the sync bit is in the high-order position. The
serdes is stopped to allow time for the data to be
moved into read/write storage.
Cable Adapter Data Flow
Cable Adapter
----,
..--+-...,
I
Address
Switches
(Cable Thru feature)
I
I
I
I
[§l
4-14
Register
To Read/Write
Storage and
the MPU
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