Post by thread:[EE]: What is the best way to transfer data from a

Hi All, I'm designing a portable data logger. From time to time, the user has to bring the logger to a PC and transfer the collected data to it. I want to use the serial port in the PC as the interface, but I worry that the RS232 drivers may be spoiled quickly, since most of the time the RS232 plug is inserted or removed when the computer is still on. I can tell the user to turn off the power first but I don't think they will follow! Is there any solution? Are there better ways to transfer data back to a PC? The interface can be anything and doesn't just restricted to the serial port. Thanks in advance! John _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi John, Why don't you try an IR serial link. The RX module could be connected to and powered by the PC serial port. The TX side could be built into your data logger. The TX/RX speed will be slow, (600-2400). Do you need to xmit a lot of data ? > The interface >can be anything and doesn't just restricted to the serial port. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Tue, 25 Dec 2001, John Waters wrote: > Hi All, > > I'm designing a portable data logger. From time to time, the user has to > bring the logger to a PC and transfer the collected data to it. I want to > use the serial port in the PC as the interface, but I worry that the RS232 > drivers may be spoiled quickly, since most of the time the RS232 plug is > inserted or removed when the computer is still on. I can tell the user to > turn off the power first but I don't think they will follow! Is there any > solution? Are there better ways to transfer data back to a PC? The interface > can be anything and doesn't just restricted to the serial port. Well... USB is specifically designed for hot insertion, but I really wouldn't worry about it. In 20+ years of dealing with every kind of serial port known to mankind, I've never seen a problem with connecting powered up RS232/EIA-232 devices. I've dealt with multiport terminal concentrators and modem racks where it was not unusual to connect and disconnect devices regularly, and I don't think there were even notices from the normally paranoid manufacturers to only connect deviced with power off. The drivers & receivers are designed to take a lot of abuse. If it's really a concern, power the datalogger off before connecting it. Dale -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

>Why don't you try an IR serial link. The RX module could be connected to >and powered by the PC serial port. The TX side could be built into your >data logger. The TX/RX speed will be slow, (600-2400). Do you need to >xmit a lot of data ? Not really, only 64K Bytes max. each time. Is the IR serial link circuit complicated? Are there any low cost off-the-shelf modules available? _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Not really, only 64K Bytes max. each time. Is the IR serial link circuit > complicated? Are there any low cost off-the-shelf modules available? There's a very simple IrDA transceiver project in the Dec 2001 Silicon Chip magazine (http://www.siliconchip.com.au) using a pair of TFDS4500 transceiver modules (made by Vishay Telefunken) It's quite easy to use a diode and LP311 comparator or IS1U60 IR receiver if you want to go the discrete way, many many components that could be used, but the above is a lot simpler. 4-page article for that particular project, but I daresay a datasheet for the TFDS4500 is lurking on the web that would give you all the info you need. HP, Honeywell, Sharp, Optek, they're all at it. From SIR (serial, 115.2k) to VFIR (very fast IR, 16M) You're pretty much spoilt for choice -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

>Not really, only 64K Bytes max. each time. Is the IR serial link circuit >complicated? Are there any low cost off-the-shelf modules available? Hi John, Try www.rentron.com/Infrared_Communication.htm I built this with a PIC16F628 and a 40khz module from http://www.Jameco.com part # 165008. I only got mine to work at 600 baud (120ft though !) reliably. However, Rentron sells part kits or assembled units. Lots of good info on the site look around. Their was also a recent post on powering a circuit from a RS232 port, I can't find it but maybe somebody on the list can point you to that. If you have any questions on my circuit or want to look at my code let me know, it's in CCS C not asm. (http://www.ccsinfo.com) Good Luck, Kevin -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> I'm designing a portable data logger. From time to time, the user has to > bring the logger to a PC and transfer the collected data to it. I want to > use the serial port in the PC as the interface, but I worry that the RS232 > drivers may be spoiled quickly, since most of the time the RS232 plug is > inserted or removed when the computer is still on. What do you mean by the drivers being spoiled quickly? Wouter van Ooijen Van Ooijen Technische Informatica: http://www.voti.nl Jal compiler for PIC uC's: http://www.voti.nl/jal PICs kopen? http://www.voti.nl/shop -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

120 ft, do I understand that you can transmit data over a IR link at a distance of 120feet (~35 meters). That would be a nice solution to a perimeter monitor. If you can get 120feet sending data I should be able to get further just detecting a signal. Justin {Original Message removed}

> 120 ft, do I understand that you can transmit data over a IR link > at a distance of 120feet (~35 meters). That would be a nice > solution to a perimeter monitor. If you can get 120feet sending > data I should be able to get further just detecting a signal > > Justin I tried once. Found you need a fair bank of IR LEDs (=power !) because you lose so much as scattered light. Very careful control of carrier frequency and rejection of ambient IR (both electronically and mechanically) were hard work. It did the job, after a fashion, though I reckon you get more bang for your buck with an IR laser diode, but YMMV -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Hi Justin, I put the circuit from the Rentron page below together and tested it in my corporate building at night, direct line of sight, dim lighting conditions, and was able to send my test pattern at 120ft. The test pattern was a repeating string of 15 characters. I tested it around the house and had no problems in a room (not direct line of sight), I also just remebered, I did test it outside on a cloudy day up to 75 feet, I did not try the full range that day for some forgotten reason. If you have any other questions, let me know. I just got back from a short vacation and will be checking my email again :) Kevin >120 ft, do I understand that you can transmit data over a IR link at a >distance of 120feet (~35 meters). That would be a nice solution to a >perimeter monitor. If you can get 120feet sending data I should be able to >get further just detecting a signal. > >Justin > >{Original Message removed}