thanks for all that help

thanks for all that help,
am thinking that the long runtime for the plc program and the
bits errors during the signals transmission in wires are two weakness points in using the plcs in the aircraft control surfaces.
what do u think about that?
and thanks again

I think it is ironic that we are on the door step of war and all of the sudden, we are getting an onslot of aviation questions by people from Egypt. What is your purpose for asking so many questions?

Now, pardner, let's not go gittin' all Xenophobic hyar. We ain't goin' t' war with Egypt, and there ain't amymore connecshun b'tween Egypt and Iraq than there is b'tween Ireland and Italy!

If the info any enemy kin git off'n this hyar web site is goin' t' compromise American security, then we is screwed already!

I agree with Tom, Egypt is not an enemy but considered our friends. If it were Iraq I might suspect the motives. However, people are people and the best way to defeat an enemy is to make him your friend. Then your enemy no longer exists..

mavric said...

"...am thinking that the long runtime for the plc program and the bits errors during the signals transmission in wires are two weakness points in using the plcs in the aircraft control surfaces.
what do u think about that?..."

To answer your question... sorta...

As is often the case, and a common answer to many questions, here-abouts...

It Depends!

PLC's, like any electronic device, can run forever if they are operating in an acceptable environment... Temperature and Vibration are a couple of factors that come to mind immediately.

Now, as far as maintaining "Data Integrity", be it stored data or I/O data, as long as the PLC is operating in an environment that is acceptable, the question of signal-integrity is really an issue concerning the sensors themselves, and the wires and connections between the sensors and the PLC. That is not a PLC reliability issue.

As long as the environment is tolerable, for the PLC and the sensors, and the connections are maintained, then there is no question of I/O Integrity.

Oh, yes... There is also the issue of the program... it should be a solid, working program without "bugs"! (Don't ya just hate 747's with bugs in their "Collision Avoidance" programs?)

Environmental Specifications are usually provided with each PLC.

In lieu of a PLC, you can also look at SBC's (Single Board Computers). The latest versions, in fact, almost all versions, run circles (speed-wise) around any standard PLC.

PLC's have a minimum scan time. This encompasses the minimum amount of time necessary to perform house-keeping chores. Once you introduce a program, the scan time gets longer. If you were to incorporate several PLC's (a single PLC at each timing-critical area, and then networked all of the PLC's together to a Master PLC then each critical area would be handled within reasonable time constraints. Meanwhile, the local PLC's would be reporting back to the Master PLC.

The Master PLC would be taking in Pilot-Input as well as Critical Circumstantial Input from various uncontrolled sensors. Those might include Radar - for Collision Avoidance, or ICE on the Wing sensors, or the "Someone just flushed the toilet" sensor, or, the dreaded, "Stewardess, My Drink is Dry" sensor,... the list goes on, and on...

Terry, I believe NASA uses old 486 type technology for its shuttles, some say because its reliable and proven, others because thats just how old they are.

I read somewhere that one of your US missile frigates was controlled entirely by an AB PLC5 system.

But what the hell do they use on those new drone type aircraft. You guys flew a long range one from Australia to the other side of the globe in a test recently for a successful landing. Now thats reliability.