Chapter 6
VXIplug&play for the VME-MXI-2
© National Instruments Corporation
6-11
VME-MXI-2 User Manual
System Controller
You can use the System Controller control to determine whether
the VME-MXI-2 acts as the MXIbus System Controller. When
the Auto setting (the default setting) is active, the VME-MXI-2
automatically can sense from the MXIbus cable whether it should
be the controller.
You can select either Yes or No to manually determine if the
VME-MXI-2 should be the MXIbus System Controller. You must
still be certain to cable the MXIbus system appropriately when you
make either of these selections.
Bus Timeout
The MXIbus Bus Timeout (BTO) is a watchdog timer for transfers
on the MXIbus. The MXIbus BTO unit operates only when the
VME-MXI-2 is acting as the MXIbus System Controller. The
functionality of this control is similar to that of the Bus Timeout
control described previously under the VME Bus Settings section. The
options range from 8
µ
s to 128 ms, with a default value of 1 ms.
After the specified amount of time has elapsed, the BTO circuitry
terminates a MXIbus cycle if no slave has responded. The BTO
circuitry is automatically deactivated when the VME-MXI-2 is not
acting as the MXIbus System Controller. The BTO is also disabled
when the current MXIbus cycle maps to the VMEbus through a
VME-MXI-2.
Transfer Limit
You can use this feature to control how many data transfers the
VME-MXI-2 will perform on the MXIbus before releasing it to another
master device that is requesting use of the bus. The default setting holds
the MXIbus for an Unlimited period of time.
The other options you can choose from are 16, 64, and 256 transfers. If
you do not want the VME-MXI-2 to hold the MXIbus for an unlimited
period of time, you can use this control to select one of these values.
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