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Doug ,
That sounds really neat. I've done some programing in the past and I have
VB on my computer and have only used it on a limited basis. Are you saying
" the down side is the start up speed" by that you mean you wouldn't want
to sit there at the bottom of the ocean waiting for windows to do its thing? re
boot or whatever.
Brian
----- Original Message -----
Sent: Saturday, April 02, 2005 11:00
PM
Subject: Re: [PSUBS-MAILIST] computers in
subs
Brian
I have a PC104 card which is really just a single board Pentium PC
compter with connectors for video, keyboard, mouse, serial, IDE drive, 10/100
network, and a Disk-on-Chip socket all on a card that is 3.5 inches
square. I run Windows98, but any Intel OS could be used.
Other cards can be connected to the main card with a 104 pin buss, so you buy
add-on cards with things like analog to digital converters, and digital I/O,
even GPS and Radio modems. I have a 30 pin Digital I/O add-on that lets
me read switches and encoders, and control relays with the addition of a
driver chip. The code to read and write the I/O lines is good old VB
that uses an API that came with the Digital I/O card. I have a 3rd PC104
card that is a DC to DC converter that allows me to power the PC104
stack and an IDE hard dive from an 8 to 30 volt DC
supply. All stacked together the PC104 stack is about 2 inches
high. The price tag for everything was about $600 and everything
but the power supply came from eBay. I was using this setup to run
a small autonomous robotic vehicle and I programmed and complied directly
on the PC104 by linking it to my laptop with PCAnywhere. The
down side to this is of course the startup speed should the system
crash. If your only monitoring systems then perhapse that is
acceptable.
Given a choice I'd go with Cliff's setup, but since I can not afford
that, I actually prefer the OOPic solution. The code is VB style, the
restart is fast, it has both analog and digital I/O, you can expand
it by adding a second unit. The units can be networked togther, they can be
networked and intergrated to you laptop, and at $89 pluss $20 for the LCD
Display, and $5 for a joystick, you sure not going to beat the price.
Best wishes
Doug Jackson
In a message dated 4/2/2005 9:34:20 PM Central Standard Time,
dr_redus@devtex.net writes:
Brain,
I am not aware of any.
Cliff
----- Original Message -----
Sent: Saturday, April 02, 2005 7:44
PM
Subject: Re: [PSUBS-MAILIST]
computers in subs
Cliff,
Do
you know if there would be any way to program a workable system using
VB , I guess you would use a lap top?
Brian
----- Original Message -----
Sent: Saturday, April 02, 2005 9:29
AM
Subject: Re: [PSUBS-MAILIST]
computers in subs
Doug,
My background is in mechanical engineering. This was my first
hands on project with a PLC. I found working with the PLC to
be straight forward. The documentation that comes with the
Automation Direct is detailed and very usable with lots of
examples. Also the tech support from Automation Direct was
great. I think this is generally true for all the PLC suppliers.
Anyone that has done any programming in C, VB or even FORTRAN (I'm
dating my self) would have no problem picking up PLC ladder
logic. My starting point was to make a list of the what I/O I
wanted in my boat such as, for example, an analog input would be a
pressure transmitter for ambient water pressure or tank pressure.
A digital input channel would be something like the hatch switch or a
limit switch or a button on a joystick. An Analog output would be
like a PWM signal to a proportional pressure regulator and digital
output would be, as an example, a coil on a solenoid valve for
air to blow the main ballast tank. After you know how many input
and output channels you will need, then you can look at the PLC modules
and decide how many you need of each. This will set the number of
slots you will need in the PLC base. My suggestion would be to have a
least one open slot for future changes. After plugging in the
modules, it is a matter of programming each module. My learning
curve was greatly helped by a fellow PSUBer, Alec Smyth, who sent me a
copy of his ladder logic. By studying what Alec had done and
reading the documentation from the PLC vendor, I was able to come up to
speed without to much grief. I did find the instruction set
available on PLC's to be primitive relative to higher level languages
such as C or VB. Most sensor manufacturers offer either 0-5VDC
output or 4-20mA outputs. After discussions with an engineer that
does a lot of mobile automation work, I choose to go with 0-5VDC
for my sensors. Anyone with basic skills in electronics ( can use
a multimeter and can solder) can pick this up. As to
PC104 experience, I have none. One suggestion I would make is to
stick with one PLC vendor for all the modules and the touch screen
display. This makes trouble shooting a lot easier. One other
point, if you have any sensors that require RS232 communication in
ASCII, you have make sure the CPU module you pick support receiving
ASCII as some do and some do not. One of the good suggestions I
received from a fellow psuber that had fabricated a psub was to wire up
all the instrumentations and equipment on the bench in approximately the
correct location prior to installing in the boat. This
proved to be very helpful in debugging everything and in
making up the wiring harness with disconnects. Part of my
interest in building a psub was to come up to speed on PLCs and
instrumentation. This part of my fabrication has been a lot of
fun. I did not buy any specific books on instrumentation. I did do
a Google search on basic instrumentation wiring and found quite a bit of
guidance. The real work in using a PLC as the onboard computer has
nothing to do with the PLC, it is having a good plan of how each ship
system is going to operate and interface with the overall
design.
Cliff
----- Original Message -----
Sent: Saturday, April 02, 2005
9:03 AM
Subject: Re: [PSUBS-MAILIST]
computers in subs
Cliff
Yup, that is out of my budget. But I have a friend, and fellow
sub builder that wants to go all out on his control and
monitoring system including the touch screen. So what is the
leaning curve for PLC and the required electronics of sensor
integration? And what web, book, and or training resources would
you recommend for someone with beginner digital electronics abilities
and good object and structure programming skills, but no PLC?
Is automation control your field of work, or did you develop this
skill for your sub? And so do you have experience with PC104 ( www.pc104.org) and would that be a
better approach for someone with C or VB experience but no PLC?
Thanks again
Doug
In a message dated 4/2/2005 8:38:24 AM Central Standard Time,
dr_redus@devtex.net writes:
Doug,
The cost breakdown for the Automation Direct PLC system on my
boat is: PLC hardware $2183, Software $394, color touchscreen
display $745 and joystick $469 for a total of $3791. If you are
patient and know what you want, you can pick up I/O modules on Ebay
at a significant discount. As an example, an Ebay search
string Automation Direct will usually turn up a list of available
PLC modules.
Cliff
----- Original Message -----
Sent: Saturday, April 02,
2005 12:41 AM
Subject: Re: [PSUBS-MAILIST]
computers in subs
Simon,
I know it's out of my league, but out of curiosity, what is
the price tag for that setup?
Thanks --Doug J
Simon,
For the 1 atm sub I have under
fabrication, I am using an Automationdirect (http://web4.automationdirect.com/adc/Home/Home),
DirectLogic 205 series PLC (Programmable Logic Controller)
with a 6" color touch screen display which is used to
interface with the controller and for all gage displays.
The PLC base has 9 modules, 1 CPU, 3 analog input, 1 digital
input, 1 RTD input, 1 analog output and two relay output
modules. The PLC is currently configured with 20 analog
input channels, 12 digital input channels, 4 RTD temperatures
inputs, 4 analog output channels, and 18 relay output
channels. The CPU module (DL 260), which is about
the size of a bar of soap, has two RS232 ports, one of
which is used to connect to my compass/roll/pitch sensor and the
other is connected to the touch screen display. A dual axis joy
stick is used for roll and pitch analog input to the
PLC and a potentiometer on the rudder pedals is
used as an analog input for yaw control. The joystick
has 6 switches that I use for blowing and flooding the MBT
and VBT as well as moving the trim weight forward or aft via
a power screw driven by a hydraulic motor. This
setup gives me fly by wire capability. A laptop
PC was used to write the ladder logic, design the screens and
download the ladder logic and screens into the PLC. All is
working fine on the bench and I found the system to be quite
flexible in changing inputs and outputs to the PLC and modifying
display screens.
A PLC was chosen over a hardened PC
for robustness and to minimize space. The PLC is powered from
either the main battery bank (120 VDC) via a DC-DC
converter (120 VDC to 24 VDC) or from an independent
emergency battery pack (24 VDC).
Cliff
----- Original Message -----
Sent: Friday, April 01,
2005 5:08 AM
Subject: [PSUBS-MAILIST]
computers in subs
NEW
TOPIC!!
Who uses onboard computers on their subs? Are
you using modified
trimix SCUBA computers, or homebrew type
stuff?
Simon,
You mean a dive computer or a normal? On
a 1 atm sub a deco computer makes no sense.
If my sub is operational again; I
consider a pocket pc for instument reading ,listing
checklists, gps navigation and as video camera
display/capture.
There are probably more possebilities
and it might save space.
disadvantage: not water
resistant
regards Emile
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