I need big time help with RS-232

[mrblonde]

I appologize for posting this type of problem here but I am out of options. I have a automatic gate program for our building. There is a wall jack for the gate that has an RJ-45 out on it. It came with a cable that goes from an RJ-45 (from wall jack) to a female DB25 (to computer). The only 25 pin I have on the pc is a female also. I tried using a male to male cable to connect the two but it didn't work. Here is why (I think) it didn't work and where this gets tricky and confusing for me. The gate software (on my PC) tries to establish communications using com1 through com4. Is the RS-232 a com port? I thought it was only used for printers...) If not how can I get my Win98 SE to associate it with being Com3 or Com4 (Com1 & Com2 are taken up by so palms; they are both DB9 male) HELP.

Mr. Blonde

 

[Guest_imported]

RS-232 is a communications standard which is applied to Serial interfaces. Most serial ports on personal computers use the RS-232 standard. Serial ports can be used by many different devices, including printers. However, many modern printers now use the parallel port (LPT), or even the USB port.

What you need is a convertor to go from your gate cable DB25 (25-pin) to a DB9 (9-pin). The convertor will have a male DB25 to a female DB9. This will then plug into one of the 9-pin serial connectors on the back of your PC. These convertors are available at most computer stores, Radio Shack, Tandy, PC World, etc.

I don't understand what you say is connected to COM1 and COM2 on your PC, but if they are both in use, then you will need to fit an additional serial port. This will be a card which plugs into one the unused slots on your motherboard. The card will need to be configured (jumpers or dip switched) for either COM3 or COM4, and have an unused IRQ (maybe IRQ5 or IRQ10 for example) assigned to it.

Hope that helps... Good luck!


ROGER - GØAOZ.

 

[edfair]

You may also need to jumper some connectors on one or both ends to get this stuff to work.
You may also need to switch the transmit and recieve lines depending on the interface to the gate.
First requirement will be a DC voltmeter to test voltages.
The 25 pin female on your computer is the printer port. Plugging a serial line into it may kill it. Ed Fair
efair@atlnet.com

Any advice I give is my best judgement based on my interpretation of the facts you supply.

Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[mrblonde]

I appreciate the responses guys... I don't understand how why these people recommend the DB25 route. They offer a DB9 female connector as well, but the manual specifically says to use the RS-232 port. I've ordered the 9 pin connector. My two other com ports have palm pilots on them so I will need to install a pci card. When it comes to configuring the ports to 3 & 4 (if I add two) is that difficult? I heard a mention of jumpers...?

Thanks
Mr. Blonde

(I believe you have my stapler...)

 

[edfair]

d9 and d25 are basically the same 232 port with different pins. Haven't had any experience with pci serial ports but based on previous interfacing I would put the palms on the pci and use 1 and 2 as your gate controls.
To change to d9 will require a rj45 to d9 adapter and pins 2& 3 swapped and pin 7 becomes 5. The handshaking is dependent on what is wired into the d25. Ed Fair
efair@atlnet.com

Any advice I give is my best judgement based on my interpretation of the facts you supply.

Help increase my knowledge by providing some feedback, good or bad, on any advice I have given.

 

[Guest_imported]

As regards your being recommended DB25 rather than DB9, perhaps the sales company wrongly surmised that your PC would have a DB25 port connector available. Modern PCs invariably have two DB9 serial ports built onto the motherboard. The differences between DB25 and DB9 are insignificant, and to all intents and purposes can be ignored. The DB9 to DB25 adaptor should work fine...

As regards Ed's suggestion, before you move everything over to different ports, check the gate software and see if it makes any reference to needing specific serial ports or IRQs in order to work. If it says it will only work with COM1 or COM2, (IRQ4 or IRQ3) then you'll need to move one of your palm pilots over to a new serial port. Otherwise, see if the gate software works on your new port first...

Assuming that the cable from your PC to the gate (RJ45) was originally supplied specifically for this task, then you probably won't need to alter any wires at the gate end.

I'm not sure if this is something you've inherited that never worked, or if it's a (relatively) new installation. If the latter, then why isn't the supplier/manufacturer giving you technical support?


ROGER - GØAOZ.

 

[Guest_imported]

As stated above, RS-232 usually refers to a serial port. Pluging it into your printer port ( the only DB25 on most modern compters). Most of the RS-232 I have worked with have had a seperate card.

???? are you running CAT 5 cable or are you running RS-232 cable???

According to RS-232 standards, an RS-232 Signal running @ 9600 has an approx. distance of 50 Ft.

What I have had to do was buy 2 Line Drivers which took my signal shot it over CAT 5 then converted it back to Db-25.

I must warn you. Kinda of have and idea about this stuff becasue it gets deep. (it's an older technology)

Things you need to know.
is the gate DCE/DTE
Where is the clock Supplied
What is the Speed of the signal.

I bought my line drivers at Black Box.
If your still lost after this give there Tech Support a call they are pretty Good

 

[bjverzal]

I think you hit on it. The DB-25 on the computer is a Parallel port, not a serial. It does not run RS-232. It runs a Centronics Parallel protocol. You can get a Parallel to Serial converter from BlackBox, but you'll pull your hair out trying to get the device working on a parallel port.

Bill.

 

[MrRick]

I think your best bet is to just buy the PCI card with the proper DB9 output.

Good luck and let us know

 

[mrblonde]

Thanks for all the responses. They unknowingly (I think thats a word) sent me the wrong cable. I used the rj-45 to db9 converter and added a pci card with two more com ports.

Problem solved. Very educational responses though...

Thanks again.
Mr. Blonde