VXI SM8000 user manual Control Register

VXI Technology, Inc.

Control Register (cont.)

		0 = BBM/MBB operation on this plug-in module is disabled
		1 = BBM/MBB operation on this plug-in module is enabled
		Pon state = 0
		If this bit is set, the relays on this module will be sequenced to
		effect proper BBM or MBB operation. If this bit is not set, the
		plug-in module will process the newly written relay data as
		immediate data, writing it directly to the relay driver ports. No
		BBM or MBB sequencing will take place.
		While this feature is enabled, the initial write to the module will
		start the delay timer running and begin the BBM or MBB
	BBM (Break-	operation. Since the relays are controlled by the 16-bit registers,
		only the effected 16 relays will perform the BBM/MBB operation.
D7	Before-Make) /	To overcome this fact, any subsequent writes to the module,
	MBB (Make-	during the initial delay timer time-out period, will be accepted and
	Before-Break)	processed. In addition, the delay time will be reset and begin
	Enable Bit	counting down again. Once the delay timer has timed-out (this
		indicates that the relays have settled into their BBM/MBB state),
		writes to the module will not be accepted and may result in a Bus
		Error depending on the value programmed into the delay timer.
		This is because the delay timer is reset at the end of the initial
		time-out and is used to time the final relay closure into their post
		BBM/MBB state. The module Busy signal will only complete
		once the final relay closure state is reached.
		If this bit is set and no value has been loaded into the Delay
		Register, the plug-in module will act as if this enable bit is not set
		and load all of the relay drivers with immediate data.
		*This bit is unused on the SM8000 and should always be sent to 0.
		0 = BBM operation on this plug-in module is selected
D6	BBM/MBB Select	1 = MBB operation on this plug-in module is selected
		Pon state = 0
	Bit
		*This bit is unused on the SM8000 and should always be sent to 0.
D5	Access LED Fail	0 = non-active
		1 = active
	Bit
		Pon state = 0
		0 = The Openbus signal is not enabled to reset this module's relays
		1 = The Openbus signal may be selected to reset this module's
D4	Relay Reset Enable	relays
		Pon state = 0
	Bit
		Note: Bit D3 must be set to 1 also, to allow the OpenBus signal to
		reset this module’s relays

SM8000 Series Programming 49