GEI-100305 Auxiliary Drive to ISBus Interface Board IS200ADII
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ISBus
The ISBus has one controller (drop 0) and no more then 31 nodes (1-31). The master
sends out a stream of bytes containing each ISBus node's references. As the nodes
receive the stream of bytes, they pass the stream on to the next node substituting
their own feedback data in place of their reference data in the stream. When the
stream of bytes return to the master, it contains each nodes feedback data.
The ISBus frame rate is programmable and can be 1, 2, 4, or 8 milliseconds (ms).
The ADII board requires a time delay of 200 µsec. This allows the LAN Control
Processor (LCP on the LDCC board) to write the drive’s feedbacks into the ISBus
controller prior to the start of the next frame. The delay time at the end of a frame is
shown in Table 1. This time is valid as long as the number of pages per the frame
rate is not exceeded.
Table 1. Frame End Delay Time
Frame
Rate (ms)
Number of
AcDc2000 drives*
End of Frame
Delay Time (µ
µµ
µs)
1 4 200
2 8 400
4 16 800
8 32 1600
*AcDc2000 drives use a double page (refer to the following timing diagram).
pg
time delay
Frame à Frame à
End Of Serial Data (EOSD)
(ADII ISBus controller introduction to LCP)
2 µs per byte (5 Mbits/s baud rate)
64 µs per page
1 page = 1 cell = 8 variables (variable = 4 bytes in length)
1 double page = 2 cells = 16 variables

Connections

The ADII board interfaces to the ISBus through two RJ45 connectors, P2 (TX/OUT)
and P3 (RX/IN). The user’s cables are run into the drive package and directly to the
ADII board.
The TX/OUT connector (P2) ties to the RX/IN connector (P3) of the next device on
the ISBus. The RX/IN connector (P3) ties to the TX/OUT connector (P2) of the
previous device on the ISBus.