Visara SCON-25L Reference Manual - Manual (Page 25)

707028-007 2-15
Chapter 2. Installation
Setting the Priority on the BTC
Determine the priority for the unit and set the priority with the switch(es) located
on the BTC-C. The priority of connection for each unit on the channel is determined
by switch settings on the BTC-C and the physical position the unit occupies on the
channel.
During normal network operation, the order of priority is (from highest to lowest):
1. All units set to High Priority, starting at the host processor and moving to the
last unit on the channel, followed by
2. All units set to Low Priority, starting from the last unit on the channel and
moving back to the mainframe.
Setting the priority to High allows the unit to attain connection to the channel
before units set to Low priority (for control unit initiated channel sequences).
Setting the priority to Low causes the unit to attain connection to the channel after
units set to High priority (for control unit initiated channel sequences).
Channel priority is set with a switch located on the BTC-C board. Set the switch
on the BTC-C board to the appropriate position for the desired priority. Bypass is
set using a switch located on the V-junction connector of the Channel Adapter
cable. Refer to Figure 2-8.
BTC-C Cabling
Typical BTC-C and CHC/CHP board cabling is shown in Figure 2-9.
To CHS or
CHC at
J3 or J8
V-Cable
BTC-C Assembly
Figure 2-9. BTC-C Typical Cabling