PDD205A1121 3BHE025335R1121控制器模塊，ABB使用配置手冊
雖然從地址修改器寄存器中的所有位可以動(dòng)態(tài)更改，但必須更改僅當VMEchip控制VMEbus時(shí)。更換從機的建議步驟地址修飾符為：a、 在請求程序配置中設置DWB位注冊到1。
b、 讀取DHB狀態(tài)位，直到其為1。c、 更改從地址修改器寄存器。d、 將DWB位清除為0。寄存器允許軟件對地址進(jìn)行編程由MVME147驅動(dòng)的修改器代碼VMEbus循環(huán)。這五個(gè)位與AMSEL結合，允許軟件動(dòng)態(tài)選擇主機訪(fǎng)問(wèn)的地址空間在VMEbus循環(huán)期間。
PDD205A1121 3BHE025335R1121控制器模塊將這五位中的任何一位設置為1都會(huì )導致驅動(dòng)相應地址修飾符行的主機高（如果AMSEL位設置為1）。將任何位清除為0會(huì )導致主機驅動(dòng)對應線(xiàn)路為低電平（如果AMSEL位設置為1）。這些位由SYSRESET清除。位7軟件使用AMSEL控制位定義VMEbus期間由主機驅動(dòng)的AM代碼源周期將位設置為1會(huì )導致主機驅動(dòng)將六位降到地址修飾符行上。沒(méi)有嘗試用于檢查存儲在此寄存器中的值是否保留或非法的地址修飾符。清除AMSEL位使主機確定AM動(dòng)態(tài)編碼。AMSEL通常應清除為0。該位被清除系統重置。該寄存器用于使MC68030能夠響特定VMEbus中斷請求。請注意PCC中的主中斷啟用位也必須設置讓VMEbus IRQ連接到MC68030。設置第1位到第7位中的任何一位都會(huì )取消屏蔽中斷來(lái)自VMEbus IRQ信號的請求相應級別。請記住，只有一個(gè)VMEbus主機可以處理VMEbus IRQ。軟件應設置這些位照著(zhù)這些位通過(guò)任何重置被清除。
Although all bits in the slave address modifier register
may be changed dynamically, they must be changed
only when the VMEchip has control of the VMEbus.
The recommended procedure for changing the slave
address modifier is:
a. Set the DWB bit in the requester configuration
register to 1.
b. Read the DHB status bit until it is 1.
c. Change the slave address modifier register.
d. Clear the DWB bit to 0. The register allows software to program the address
modifier code that is driven by the MVME147 during a
VMEbus cycle. These five bits, in conjunction with AMSEL, allow software to
select dynamically the address space that the master accesses
during VMEbus cycles. Setting any of these five bits to 1 causes
the master to drive the corresponding address modifier line to
high (if the AMSEL bit is set to 1).
Clearing any of the bits to 0 causes the master to drive the
corresponding line to low (if the AMSEL bit is set to 1).
These bits are cleared by SYSRESET.
Bit 7 Software uses the AMSEL control bit to define what is the
source of the AM code driven by the master during a VMEbus
cycle.
Setting the bit to 1 causes the master to drive the contents of the
lower six bits onto the address modifier lines. No attempt is
made to check the value stored in this register for reserved or
illegal address modifiers.
Clearing the AMSEL bit causes the master to determine the AM
code dynamically.
AMSEL should normally be cleared to 0. This bit is cleared by
SYSRESET. This register is used to enable the MC68030 to respond
to specific VMEbus interrupt requests. Note that the
master interrupt enable bit in the PCC must also be set
for VMEbus IRQs to get through to the MC68030.
Setting any of bits 1 through 7 unmasks an interrupt
request from the VMEbus IRQ signal at the
corresponding level. Keep in mind that only one
VMEbus master is allowed to handle each level of
VMEbus IRQ. The software should set these bits
accordingly. These bits are cleared by any reset.
