1756-CNB模块,1756-CNB产品重量
双数字输出（DDO）模块
接收来自主电源的输出信号
单个并行处理器或串联路径，并应用3取2
每个人的投票过程转换开关产生一个
输出信号，然后传递给现场终端。而quadru在TMR上复制了输出电路
模块提供多重冗余对于所有关键信号路径，双电路提供了足够的冗余，以确保安全运行。DDO
模块针对安全关键控制程序进行了优化
成本比最大值更重要可利用性
DDO模块具有电压环回验证以下各项操作的电路
每个输出开关独立负载的存在并确定
1756-CNB模块是否存在潜在故障。的故障
检测到的磁场电压与输出点的指令状态激活负载/保险丝报警指示灯。
此外，正在进行的诊断包括在每个通道和电路上执行
DDO模块的。任何通道上的任何诊断故障都会激活故障指示灯，依次激活
底盘报警信号。双模块在以下人员在场的情况下正常运行
大多数单一故障，可能会运行正确地使用某些类型的多重
故障，但卡死故障是例外如果其中一个输出开关
有卡在关闭位置的故障，输出转到可能出现关闭状态和故障
切换到热备盘期间单元
DDO模块支持热备盘能力，允许在线更换
出现故障的模块。每个模块机械键控以防止
配置中的安装不正确底盘。
DDO模块需要单独的外部终端面板（ETP），带有
Tricon背板的电缆接口。
数字输出设计为源现场设备的电流，so现场电源必须连接到每个输出
现场终端上的点。
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.
