yet another basic laptop question - LPT/COM port

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BlueSkyNick

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i've got an small (old) Dell which has no serial port, only a USB and a printer port. I am putting my AIS output into the USB via a convertor. This only includes lat/long (RMC) from the GPS - I am losing all the other NMEA stuff.

My Maptech software (the new CNP version) will take data from multiple COM ports. I could buy a mux for a couple of hundred euros, or set up a hub on the USB port.

The simplest method is, with the help of a 2 quid gender bender, to put the second input into the printer port.

Despite a certain amount of trial and error, I can't assign a COM port to it, instead of LPT.

Am I barking up the wrong tree, or just plain barking ??
 
You can't turn a parallel (LPT) port into a serial (COM) port - even if you use a convertor to sort the "wiring" the communication protocols are completely different.

Best option would be to use an RS232 (9 pin serial) to USB converter. If you are already using all your available USB ports - you can use a "hub" to give you an almost limitless number of connections.
 
I have been working with a four-port USB hub for years without trouble, and have connect Serial-USB converters to the hub without problems.
 
One of the problems in usung a hub is that it is not always compatible with older NMEA gear, particularly older autopilots, which require a greater "on" voltage than an unpowered hub can provide, typically 3-5 volts, whereas an unpowered hub will only swing in the region of 2V, or maybe just a bit more.
On my boat the Prolific serial USB convertor refuses to run the ST 6000 Autopilot of Early '90's vintage, but the Keyspan USB converor will, as will the 2port PCMCIA adaptor and the four port USB serial adaptor.
The more unpowered devices you put in the usb chain the more chance there is of not achieving the required switching voltage.

Steve
 
You've moved on, but you were mixing up the connector with the signal type - just because it has a certain type of plug doesn't mean that it necessarily delivers a certain type of signal, the computer industry is not that sane! Iirc IBM adopted the 25-way D-type as a parallel port connector on the IBM PC because they couldn't fit both the standard Centronics IDC socket and another port on the backplate of a PC expansion card.

FWIW

Steve
 
[ QUOTE ]
CPC do a single USB to Four Port Serial Convertor for £32.
It would be wiser to use this rather than a USB Hub.
Part Number CS 12792.
www.cpc.co.uk

Hope this helps

Steve.

[/ QUOTE ]Now got this in and working, and its great!|

Unit received next working day after order.

Only one snag for others to be aware of:

PC New hardware wizard came up, loaded software from CD (ignoring the warning about no Windows logo), but then New Hardware wizard came up repeatedly.

Phoned CPC's number, they commit to returning calls within 2 hours, so not instant service but much better than a lot of others.

Their man set up a unit into his own laptop and talked through the procedure - also excellent, because it meant he wasnt working from a script or guess work. He explained that I had to load the drivers 4 times as it is a 4 port device. Did that, but now for the catch - also had to go through the 'Update Drivers' procedure on the disk.

No idea why, but it made the whole thing work properly in less than 10 minutes.

Now have my Maptech Chart Navigator Pro displaying AIS information as well as all NMEA data, ie heading, depth, wind speed and direction, etc - really is the dogs bits. Well pleased !

THanks to all for their advice.
 
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