Connect cable to remote with computer on or off?

bgc99 · Post by **bgc99** » Wed May 26, 2004 9:44 pm

Hi,
I'm waiting on a JP1 cable that I ordered and thought I'd ask this. Does it matter if the cable is connected to or disconnected from the remote while the computer is running or does that require a shutdown?

Thanks,
BGC

johnsfine · Post by **johnsfine** » Thu May 27, 2004 4:58 am

It doesn't require any such precautions. Printer ports are designed to be connected and disconnected with power on anyway and the JP1 cable has resistors limiting the current flow in case it is connected wrong.

hhyatt · Post by **hhyatt** » Sat Aug 21, 2004 7:03 pm

I had always heard NOT to change LPT connections with power on. I have an AB switch that I have printer and JP1 interface connected to. Based on past instructions, I always power down before changing from one to the other. I know that USB can be hot-switched, but I thought that LPT could not. Furthermore, the source that I got this from x years in the past said that hot-switching LPT could damage the computer.

What have other heard, or better still can you point me to a definitive resource that says that hot-switching LPT (parallel/printer) ports is allowed?

Filebug · Post by **Filebug** » Sun Aug 22, 2004 4:38 pm

Isn't flipping the switch on your A/B box the same as manually unplugging one parallel device and plugging in another?

I agree I have always heard never hotswap anything from your LPT port and have heard the same with the PS2 ports. Of course I've never powered down and have never had or heard of anyone having a problem from not powering down.

zaphod7501 · Post by **zaphod7501** » Sun Aug 22, 2004 5:19 pm

As an electronic tech I think your biggest worry would be static electric discharge damaging the PC (and this would be the same possibility even if the PC was turned off). Mechanical A/B switches (as opposed to electronic) generate a lot of electrical NOISE , personally I would be more likely to power down the PC with one of them than than if I was going to swap cables. There is basically nothing in the JP1 interface (unlike a printer) so I think the most important thing would be to make sure the printer was powered down before disconnecting it.

classicsat · Post by **classicsat** » Mon Aug 23, 2004 12:08 pm

Doesn't matter, I connect/disconnect JP1 and aother bit-banged LPT port programmers with no ill effect to the PC or device.

hhyatt · Post by **hhyatt** » Mon Aug 23, 2004 4:42 pm

So it seems that there is little, if any, concern for hot-swapping/hot-switching LPT ports. What was the concern in the past -- I have seen this as a standard of practice in published literature.

The comment about static surges would seem to have the best foundation -- is this because the LPT to standard printer is a relatively high current application while JP1 is elecronically isolated and uses virturally no current ??

This is no big issue, I just want to know what the basis of the "old rules" was. There was so much to learn that a person didn't have time to understand why -- in most cases we took a lot of things on faith.

Mark Pierson · Post by **Mark Pierson** » Mon Aug 23, 2004 4:56 pm

hhyatt wrote:I just want to know what the basis of the "old rules" was.

The old rules basically admonished you to not hot-swap anything. In the early PC days, they and their peripherals weren't nearly as tolerant as they are today. These days, I don't think the PC/port is at risk, but the newer bi-directional printers are finicky (more specifically, their drivers are).

I really don't think there's much, if any, risk with a JP1 cable. Until I went with a USB version, I was hot-swapping JP1 and my older Epson ink jet constantly. When my wife had an HP printer on her desktop, it didn't like being unplugged and then reconnected, but I'm sure it was a driver issue since it continuously polled the port (it hated the JP1 cable

).