Agilent Technologies E1439 manual Fiber Frames, Data Frame Normal Data Fiber Frame

Using the Agilent E1439

Fiber Optic Interface

Fiber Frames

Data is transmitted over the fiber interface in a series of fiber frames. Each fiber frame is composed of a series of 32-bit values, which encode to 40 bits. Each 32-bit value can either be data or an ordered set. Data and ordered sets are strung together to make the three types of fiber frames—Data Frame, BOF, and EOE. The Data Frame transmits 0 to 512 32-bit data words. The exact amount of data that is sent depends on the amount of data that is available when the fiber interface is ready to send the Data Frame. BOF (Beginning Of Frame) is a synchronizing event that can be sent just prior to the start of data transmission. EOE (End Of Epoch) is a synchronizing event that contains the last 4 data bytes in an epoch. An epoch is composed of one or more Data Frames followed by an EOE. The following shows the ordered sets and data that make up the three fiber frames:

Data Frame (Normal Data Fiber Frame)

IDLE1	SOF2	0 to 512 data words3	CRC4	FEOF5	SEOF6	GO/STOP7
BOF (Sync Without Data Fiber Frame)
IDLE1	SOF2	No data	CRC4	MEOF8	SEOF6	GO/STOP7
EOE (Sync with Data Fiber Frame)
SWDV9	SOF2	Last 4 data bytes in epoch10	CRC4	MEOF8	SEOF6	GO/STOP7

1.Pad for Data Frame or BOF

2.Start Of Frame, framing event that embeds PIO1, PIO2, and DIR

3.32 bit or 4 Byte words, maximum 2048 Bytes

4.Cyclic Redundancy Check, optional

5.Frame End Of Frame, end of Data Frame

6.Status End Of Frame, embeds FIFO OV and NRDY

7.Flow controls

8.Mark End Of Frame, end of BOF and EOE

9.Sync With Data Valid, start of EOE

10.4 bytes, exactly

Control Signals

PIO1, PIO2, DIR, and NRDY are FPDP (front panel data port) control signals. These signals can be defined by another product or you can define their meaning and application.

When an overflow condition in the transmit FIFO occurs, the E1439D asserts FIFO OV indicating a loss of data. This may occur in Append fiber mode if the available fiber bandwidth capability is exceeded.

If flow control is enabled, the E1439D responds to the STOP and GO signals. See “Generate” on page 48 for details.

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