Fw: [PSUBS-MAILIST] Integration of instruments:

I suspect this is your line of work eh Rick?

From:  "rick miller" <rickm@pegasuscontrols.com>
Reply-To:  personal_submersibles@psubs.org
To:  <personal_submersibles@psubs.org>
Subject:  Re: [PSUBS-MAILIST] Integration of instruments:
Date:  Sun, 11 Dec 2005 12:16:36 -0800
>mike
>
>       this is a just  comm interface, nmea protocols which are
>based on rs 232 or rs 422 twisted pair comm are just the industry
>agreed adress and value number using fixed ascii values . you can
>config any lap top to talk to these devices. the basic protocol is
>one master and all slaves.  Lets look at the type of integration
>required in a psub.
>
>    instrumentation integration for a psub
>    instrument            protocol            value
>    depth of water         nmea                ascii
>    heading                    nema                ascii
>    gps                          nmea               ascii
>    depth                       none                4-20 ma/0-10
>volt
>    tank presssure          none               4-20 ma/0-10 volt
>    o2/co2 sensors         none               4-20 ma/0-10 volt
>    battery voltage          none                0-10 volt with
>dividers
>    digital i/o                   none                voltage based
>input/output
>
>why all the different comm types/ sensor interfaces?
>
>    most sensors that only give a single value will be a 4-20ma or
>voltage output, while sensors that give more than one value worth of
>info will have some type of serial ascii interface. however there
>are also serial comm to current or voltage converters especially for
>depth and heading sensors.gps has to much info to allow for
>conversion to single value data types.
>
>    integrated consystem costs can be as low as several hundered
>dollars to as hgih as 10's of thousands of dollars depending on the
>bells and whistles.
>
>    primary points for system design
>    1. decide the typeof hmi wanted/human machine interface
>        lcd screen
>        lights and buttons
>        monitor with or without touch screen
>
>    2. type of system control wanted
>        auto depth control
>        auto heading control
>        alarm types/ low pressures/ low voltage/flooding
>        drive system interface
>
>    3.type of controller wanted
>        plc/ programable logic controller
>        pc based control
>        pic/micro controller
>        single function controller
>
>     pic    this type of controller used is normal based upon the
>amount of data needed. Most pics only have four analog chanels but
>they can be up graded to more this type of controller is what is
>used in most of the electronics what we see today. and is often
>refered to as embeded contoller.
>
>    plc/programable logic controller
>    these controller are the standard for industrial con systems due
>to the large quanity of equipment and options available for them.
>normally you pick a manufacture and they will provide all of the
>equipment /interfaces and software for the system, you just have to
>write the control logic. While pc's are used for the hmi they never
>controll the process. pc's are considered to be to unreliable for
>process control.
>
>    pc based control
>    dont do it/ use a pc for data capture only.
>
>cost consideration vrs skill level
>
>    pic's relativly cheap about  100.00 but will require custom
>circuits to be designed and the ablity to program the controller
>using one of several languages. normally  little to non manufacture
>support.
>
>    plc's start at several hundred and go up, a basic system with a
>basic hmi can cost several thousand dollars. but allows for multiple
>type of sensors without making custom circuits, and the software is
>normally easier to write, and most manufastures have great customer
>support. i prefere allen bradley for this type of control.
>
>    pc's. there are several types of data aqusistion devices and
>software for pc,s available on the market today . Ranging from
>several hundred dollars to several thousand dollars. as i said
>before do not use these systems for control only data storage.
>
>    single function controller/ pid controller
>    as the name says they will control only one funtion/ sometimes
>two but that is just two singles in the same case, and do not
>require software programing just the tuning and setpoint input. they
>would be great for an auto depth control and or heading. and they
>cost about 500.00$
>
>    sorry to get so long winded
>
>rick m
>
>----- Original Message ----- From: "Michael Holt"
><mholt@ohiohills.com>
>To: "Personal Submersibles List" <personal_submersibles@psubs.org>
>Sent: Sunday, December 11, 2005 10:19 AM
>Subject: [PSUBS-MAILIST] Integration of instruments:
>
>
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