1756-CNB模塊,1756-CNB產品重量
雙數字輸出（DDO）模塊
接收來自主電源的輸出信號
單個并行處理器或串聯路徑，并應用3取2
每個人的投票過程轉換開關產生一個
輸出信號，然后傳遞給現場終端。而quadru在TMR上復制了輸出電路
模塊提供多重冗余對于所有關鍵信號路徑，雙電路提供了足夠的冗余，以確保安全運行。DDO
模塊針對安全關鍵控制程序進行了優化
成本比最大值更重要可利用性
DDO模塊具有電壓環回驗證以下各項操作的電路
每個輸出開關獨立負載的存在并確定
1756-CNB模塊是否存在潛在故障。的故障
檢測到的磁場電壓與輸出點的指令狀態激活負載/保險絲報警指示燈。
此外，正在進行的診斷包括在每個通道和電路上執行
DDO模塊的。任何通道上的任何診斷故障都會激活故障指示燈，依次激活
底盤報警信號。雙模塊在以下人員在場的情況下正常運行
大多數單一故障，可能會運行正確地使用某些類型的多重
故障，但卡死故障是例外如果其中一個輸出開關
有卡在關閉位置的故障，輸出轉到可能出現關閉狀態和故障
切換到熱備盤期間單元
DDO模塊支持熱備盤能力，允許在線更換
出現故障的模塊。每個模塊機械鍵控以防止
配置中的安裝不正確底盤。
DDO模塊需要單獨的外部終端面板（ETP），帶有
Tricon背板的電纜接口。
數字輸出設計為源現場設備的電流，so現場電源必須連接到每個輸出
現場終端上的點。
Dual Digital Output Module
Dual Digital Output (DDO) modules
receive output signals from the Main
Processors along a single parallel or
series path, and applies a 2-out-of-3
voting process individually to each
switch. The switches produce one
output signal which is then passed to
the field termination. While the quadru
plicated output circuitry on TMR
modules provides multiple redundancy
for all critical signal paths, dual
circuitry provides just enough redun
dancy to ensure safe operation. DDO
modules are optimized for those safety
critical control programs where low
cost is more important than maximum
availability.
DDO modules have a voltage-loopback
circuit which verifies the operation of
each output switch independently of the
presence of a load and determines
whether latent faults exist. Failure of
the detected field voltage to match the
commanded state of the output point
activates the LOAD/FUSE alarm indi
cator.
In addition, ongoing diagnostics are
performed on each channel and circuit
of a DDO module. Failure of any diag
nostic on any channel activates the
Fault indicator, which in turn activates
the chassis alarm signal. A dual module
operates properly in the presence of
most single faults and may operate
properly with some kinds of multiple
faults, but stuck-Off faults are an
exception. If one of the output switches
has a stuck-Off fault, the output goes to
the Off state and a glitch may occur
during switch-over to a hot-spare
module.
DDO modules support hot-spare capa
bility, which allows online replacement
of a faulty module. Each module is
mechanically keyed to prevent
improper installation in a configured
chassis.
DDO modules require a separate
external termination panel (ETP) with a
cable interface to the Tricon backplane.
Digital outputs are designed to source
the current to field devices, so field
power must be wired to each output
point on the field termination.
