Snerkel

I would look at installing a router doing NAT with the port for VPN being the only thing open. Setup a VPN server on one of the RSview PCs. Make a VPN connection from your PC to the RSview PC which will allow you to use RSlinx gateway to give you full access. This is about as secure as you can make it while still giving you full network access to those PCs snd PLCs.

The 871TM is a two wire device isn't it ? I would suggest three wire devices for PLC inputs as the current drawn by the two wire proximity switch can be enough to cause the input to switch. You may be close to the switching curent with the two wire device, and slight noise on the wiring is enough to tip it over the edge.

One of the reasons these sort of things don't always get taken up is the different way they are assesed for tax purposes, though I think this may be changing. Fuel costs are taken in full from the annual profit. Assets are usually depreciated over a number of years, so only a percentage of the cost is set against profit each year, thus it takes a number of years for the bean counters to actually see the saving.

You should have taken your math one step further, the amount of voltage across the relay will be a tad over 20v, check the relay rating for the minimum pull-in voltage, if this is <= 20v then you should be OK

This may or may not work never tried it but.... Setup a fault routine. In the routine Latch S:1/8 Latch S:5/0 Unlatch S:1/13 This hopefully will set a minor error which will still stop the processor (but can be reset by key). Will unlatch the major error, and will set the reset on powerup bit.

Using a breaker as you suggest will be fine. I assume the SCR is being used for a heater system? If it is then you will probably want to look at over temperature protection that controls a contactor in series with the SCR. In normal operation the contactor remains on and the SCR controls the heating, if an over temperature is detected then the contactor is used to isolate the heating circuit. Another idea for the over temperature protection is to use a circuit breaker with a shunt trip such as this http://new.kimcontrols.com/item/G3P030STDC?man=3 Putting 24v onto the shunt trip turns off the circuit breaker so an external circuit (such as over temperature) can be used to "trip" the breaker.

Also for SCR you should look at using Semiconductor Fuses for the best level of protection.

Another addition may be to use a bagging over the water hoses, so you end up with a double skinned hose. End inside panel is sealed, end outside is open into a small tank or a bund. Level switch in the tank, any leaks no matter how small end up in the tank/bund, and even small leaks will eventually trigger level switch. System used a lot in chemical dosing.

You could make a simple mod that satisfies both requirements. You would need an additional output from the PLC such that once you get the OK signal from your relay you short circuit the relay coil (using a relay driven from your PLC) thus illuminating the lamp. Of course your existing system will not detect a short circuit as the relay would still switch, my suggestion would cause a problem if you did have a short circuit. A better system would be a series resistor in place of the relay with a resistance approx = 50% of the lamp resistance. Using an analogue voltage input on the PLC measure the voltage across the resistor a good circuit will give you about 4v across the resistor, a bad circuit will give you less than say 2v or greater than say 6v across the resistor. This circuit will also light the lamps at a reduced brightness, the advantage of a reduced voltage across the lamps is that they don't get as hot. You would need to make sure the resistor had sufficent power handling to take the full 12volt across it. If you wanted to light the lamps at full brightness then place relay contacts across the resistor so as soon as you detect a good part you can switch the resistance out of circuit.

No Reason being the description/rung comments are not stored in the PLC so unless you have the original software or a csv with the comments then you are stuffed.

As far as I am concerned Ladder is a superb RISC language. For normal use you need to know a few instructions that can be built quickly and easily into a program for controlling a complex machine or process. The structured text and basic modules have their place, but for the actual control the PLCs are made to do ladder is by far the most robust, safe, programming launguage you could find. As far as engineering staff are concerned:- Our electricians need to at least be able to see why a process has failed, ladder with good comments make it simple for even the oldest technophobe to see the fault in a familiar language. Fault finding by MONITORING the PLC code is much quicker than the traditional electrical test methods.

In the past I have used illuminated pushbuttons (with and without lamps). I then print laminated labels using a Brother P-Touch on laminate with clear background. The labels are cut to fit inside the pushbutton. I can generally create a symbol or get enough words in to convey use of button and it looks cool when illuminated.

Simple may be best, a basket fitted to the lighting rig with the cables routed so that they drop down towards centre of basket. You would just have to take your time lowering the rig to ensure the cable comes out smoothly. Hopefully the random way the cable is stored in the basket will help prevent induction problems.

Be careful if you decide to use any kind of drum as in operation you are likely to have 50% of the cable still on the drum. The inductance could easily melt your cables!

I have always found SSD drives to be good. http://www.ssddrives.com/usa/Products/DcDrives/DcDrives.php

Best thing you can do is setup a regime for modifications. A simple idea we use is to have a folder with a sub folder for each machine. Each machines folder contains a folder with the date modified as the name and a folder named old versions. The dated folder contains the software currently being used, when somebody starts to modify a machine they copy this folder and make the mods to the copy. When they finish they drag the now old version into the "Old Version" folder and rename the copied folder to todays date. It's simple but effective and has got us out of the sh1t on a number of occasions.

If it isn't already installed (not installed as default) you will find it on the RSLogix 5000 CD.

"Ironside" Never gets out of the office chair

PNP all the way. Non-grounded versus grounded. Unless a good reason otherwise always grounded. Big problem with non-grounded is that you still have the potential for two faults to then cause big problems. If you get a ground fault, eg the positive gets shorted accidently to ground... then an output cable gets shorted to ground you then have an output that appears to be on. A properly grounded system shouldn't have this sort of problem as either fault should take out a fuse.

Be careful with this one as the instructions state it isn't isolated, eg in a fault condition you could get an high voltage at the pins. We used to use an interface card that provided an isolated circuit in situations such as this.

As you are using an OB16 you can make the output proportional using a cyclic timer. To make a cyclic timer use a standard TON and put the done bit in series with the coil. ---¦/¦------------------(T4:0) T4:0/DN Use the T4:0.ACC to compare against the PID output, so using a 0.01 timebase one second equals 100. Scale the PID output to 0-100% Then use a compare T4:0.ACC < PID value -----------------------(Output) ¦ PID value = 100 ----------¦

Let us know how you get on

Using the one shot bits with a coil is the best way of using them. I like logic to be divided up. With RSlogix 500 the best way of achieving this is to create subroutines. The main routine would then only have the JSR instructions that call each subroutine. It may also be helpful to load a copy of the code so we can open it in RSlogix.

RJ45 to Phoenix cable 1784-CP14 http://domino.automation.rockwell.com/appl...F4?OpenDocument shows the pin out Be careful if you chop up a Cat5 cable instead of making one up, two of the pins in the RJ45 provide 24v DC so any unused cores need insulating to prevent shorts.

Just been checking up and the mini din to mini din cable is crossover, as is the 9pin D to mini din used for programming... therefore You need to place a cross-over cable between the 9pin D of the programming cable and the 9pin D on the AIC+ . If you don't do this the two cables will null each other. The PV only uses three connections so you could make a short adaptor cable using a male 9pin D & female 9pin D. Pin 2 -------- Pin 3 Pin 3 -------- Pin 2 Pin 5 -------- Pin 5