Longer HP-IL cable runs
02-16-2018, 04:34 PM (This post was last modified: 02-16-2018 04:49 PM by 4ster.)
Post: #1
 4ster Member Posts: 143 Joined: Mar 2015
Longer HP-IL cable runs
I am working on a project where the HP-IL controller will be around 10 to 20 meters away from the listener. HP literature says that runs up to 10 meters "using simple 2 wire cables" and up to 100 meters "using shielded, twisted pair cables" are achievable.

I don't recall seeing HP-IL cables over more than a few meters in length for sale.

Is it as simple as taking two short cables, cutting them in half and soldering in the appropriate type of cable between the IL plugs?

An HP-IL cable has two wires. Is it these two wires that are the twisted pair for the longer runs or is it the outgoing and incoming cables that are twisted together? I am thinking that at a minimum I should try to find shielded 4 conductor twisted pair cable for my extensions.

I've always assumed the 2 wires in an individual IL cable are for backup in case one wire looses continuity, since information is only flowing one direction in HP-IL devices. Is this correct?

Steve
In order of appearance: HP 41CV, CMT-MCGPS, HP 41CX, DM 41, DM 42
02-16-2018, 05:15 PM
Post: #2
 Paul Berger (Canada) Senior Member Posts: 533 Joined: Dec 2013
RE: Longer HP-IL cable runs
HPIL uses differential signalling so while data only travels in one direction, both wires are required. The manual "The HP-IL Interface Specification" 82166-90017, available on the MoHPC manual collection, gives all the details about suitable cables.

Paul.
02-16-2018, 05:36 PM
Post: #3
 Sylvain Cote Senior Member Posts: 1,755 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-16-2018 04:34 PM)4ster Wrote:  I don't recall seeing HP-IL cables over more than a few meters in length for sale.

Unshielded straight cable of up to 100 meters were produced by HP.

Extract from the HP-71 Compendium:
Code:
HP-82167A         HP-IL Cable (  0.5 Meter,  Qty 2)                           $6 : 1985 HP-82167B HP-IL Cable ( 1 Meter, Qty 2)$8 : 1985 HP-82167D         HP-IL Cable (  5   Meters, Qty 2)                          $10 : 1985 HP-11340A HP-IL Cable ( 20 Meters, Qty 2)$40 : 1985 HP-11340B         HP-IL Cable ( 50   Meters, Qty 2)                         $100 : 1985 HP-11340C HP-IL Cable (100 Meters, Qty 2)$200 : 1985

I personally have 20 and 50 meters HP-IL cables and they worked like the shorter ones.

Sylvain
02-16-2018, 09:13 PM (This post was last modified: 02-16-2018 09:40 PM by Dave Frederickson.)
Post: #4
 Dave Frederickson Senior Member Posts: 2,118 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-16-2018 04:34 PM)4ster Wrote:  Is it as simple as taking two short cables, cutting them in half and soldering in the appropriate type of cable between the IL plugs?

Pretty much. Consider using Martin's 3D-printed HP-IL connectors.

(02-16-2018 04:34 PM)4ster Wrote:  I am thinking that at a minimum I should try to find shielded 4 conductor twisted pair cable for my extensions.

Cat 5 STP Ethernet cable should work well with a differential impedance of 100 ohms, per the HP-IL spec.

Dave
02-17-2018, 05:21 PM
Post: #5
 4ster Member Posts: 143 Joined: Mar 2015
RE: Longer HP-IL cable runs
Thanks for the info, the comments were very helpful.

Seems a shame to cut two working cables in half, I'll look into the 3D printed versions and try to make them work.

Steve
In order of appearance: HP 41CV, CMT-MCGPS, HP 41CX, DM 41, DM 42
02-18-2018, 05:14 PM
Post: #6
 4ster Member Posts: 143 Joined: Mar 2015
RE: Longer HP-IL cable runs
Dumb question: I am an electronics dunce.

Can I use 2 twisted pair sets in the Cat 5 cable or do I need dedicate one twisted pair per cable?

It seems that the function of the shielding would be defeated if both halves of the HP-IL loop are in one Cat 5 cable.

Steve
In order of appearance: HP 41CV, CMT-MCGPS, HP 41CX, DM 41, DM 42
02-18-2018, 05:21 PM
Post: #7
 rprosperi Super Moderator Posts: 5,194 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-18-2018 05:14 PM)4ster Wrote:  Dumb question: I am an electronics dunce.

Can I use 2 twisted pair sets in the Cat 5 cable or do I need dedicate one twisted pair per cable?

It seems that the function of the shielding would be defeated if both halves of the HP-IL loop are in one Cat 5 cable.

You should be able to use 2 pairs in the same cable. Normal CAT5/5E/6 cables actually carry 2 distinct sets of 4 wires to implement 2 independent Ethernet lines, which can be split at both ends to make running wire simpler / cheaper. Most folks think Ethernet requires all 8 lines, but it's really just 4.

I imagine the shielding in these twisted pairs is good enough for HP-IL which runs at far lower data rates than Ethernet.

But I'm no EE either, this is just pragmatic experience.

--Bob Prosperi
02-18-2018, 06:58 PM
Post: #8
 Paul Berger (Canada) Senior Member Posts: 533 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-18-2018 05:21 PM)rprosperi Wrote:  You should be able to use 2 pairs in the same cable. Normal CAT5/5E/6 cables actually carry 2 distinct sets of 4 wires to implement 2 independent Ethernet lines, which can be split at both ends to make running wire simpler / cheaper. Most folks think Ethernet requires all 8 lines, but it's really just 4.

But I'm no EE either, this is just pragmatic experience.

Gigabit ethernet uses all 4 pairs in the cable, and CAT 5/5e/6 cables is unshielded. Ethernet uses differential signalling to reduce the effects of noise.
02-18-2018, 08:05 PM
Post: #9
 rprosperi Super Moderator Posts: 5,194 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-18-2018 06:58 PM)Paul Berger (Canada) Wrote:  Gigabit ethernet uses all 4 pairs in the cable, and CAT 5/5e/6 cables is unshielded. Ethernet uses differential signalling to reduce the effects of noise.

So, do you think these (CAT5/5E/6) are usable for HP-IL, or are you saying not suitable? Also, I think you mean the individual pairs are unshielded, not the entire cable, right?

I was going to mention Gbit Ethernet and thought "well, very few folks use this at home anyhow so why bother" but even that is increasingly untrue. With prices for Gbit routers and devices dropping every day, it pays to use them.

--Bob Prosperi
02-18-2018, 09:22 PM
Post: #10
 Paul Berger (Canada) Senior Member Posts: 533 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-18-2018 08:05 PM)rprosperi Wrote:
(02-18-2018 06:58 PM)Paul Berger (Canada) Wrote:  Gigabit ethernet uses all 4 pairs in the cable, and CAT 5/5e/6 cables is unshielded. Ethernet uses differential signalling to reduce the effects of noise.

So, do you think these (CAT5/5E/6) are usable for HP-IL, or are you saying not suitable? Also, I think you mean the individual pairs are unshielded, not the entire cable, right?

I was going to mention Gbit Ethernet and thought "well, very few folks use this at home anyhow so why bother" but even that is increasingly untrue. With prices for Gbit routers and devices dropping every day, it pays to use them.

I think Cat5 like cables would be fine and as you said you can use two pairs in the cable for the connections in each direction if you happen to have a long lobe on the loop. HPIL uses differential signalling so has some built in resistance to noise. The characteristic impedance of Cat 5 is specified as 100 ohms which is the same as HP-IL cables according to "The HP-IL Interface Specification". This manual also gives information on testing cables.

No the entire cable is unshielded it is simply 4 twisted pairs inside a plastic tube. In ethernet you do not get into shielded cables until 40 and 100 Gb wiring, but at those speeds optical fibre would seem to be more common. Cables like this are designed to be used in systems that use differential signalling over a pair of wires. In differential signalling the receiver is looking at the difference in signal level between the two wires in the pair, unlike something like RS-232 where the receiver is looking at the the signal level on a single wire relative to ground. Another common differential system is RS-422. The main advantages of differential signalling are 1. It is not ground referenced so ground shift between sender and receiver is of no concern and 2. because the conductors in a pair are in close proximity, noise impulses will affect both conductors equally without changing the difference in signal level between the two conductors in the pair, giving it very good noise immunity. The place where I have seen people get into trouble with cabling like Cat 5 is when they try using it for connections using single ended (ground referenced) signalling such as RS-232 where the lack of shielding makes it subject to induced noise plus when the two wires in a twisted pair are carrying different signals, cross talk between wires can cause problems. This is why a RS-232 cable is shielded and not twisted pairs plus it uses a connector that has a pin designated for grounding that shield. I have even seen RS-232 cables that have a foil shield around each individual conductor and then a braided shield around the whole bundle.

In my experience you can hardly buy anything these days that supports wired ethernet that is not Gb capable. This is likely due to chip manufacturers only building Gb and higher chips these days. I have seen instances where Gb controllers where used, but only 100Mb was supported due to the PHY used not supporting Gb.

Paul.
02-19-2018, 03:57 PM
Post: #11
 Dave Frederickson Senior Member Posts: 2,118 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-18-2018 06:58 PM)Paul Berger (Canada) Wrote:  Gigabit ethernet uses all 4 pairs in the cable, and CAT 5/5e/6 cables is unshielded.

CAT 5 shielded twisted pair (STP) is readily available.

https://www.amazon.com/UbiGear-Cat5e-Shi...B00BLSWPEY

or you can find shielded CAT 6 at Home Depot. Well, you have to mail order it.

https://www.homedepot.com/p/NTW-100-ft-C.../300832504

True, two of the pairs will be unused, but for an out and back run it should work just fine.

Dave
02-20-2018, 11:50 PM
Post: #12
 Howard Owen Member Posts: 86 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-16-2018 09:13 PM)Dave Frederickson Wrote:  Cat 5 STP Ethernet cable should work well with a differential impedance of 100 ohms, per the HP-IL spec.

I can confirm that cat5 works great. I have a 50 foot run that works fine.

Regards,
Howard
02-21-2018, 03:39 AM
Post: #13
 4ster Member Posts: 143 Joined: Mar 2015
RE: Longer HP-IL cable runs
Thanks!

Steve
In order of appearance: HP 41CV, CMT-MCGPS, HP 41CX, DM 41, DM 42
02-21-2018, 10:01 AM
Post: #14
 Harald Senior Member Posts: 757 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-16-2018 09:13 PM)Dave Frederickson Wrote:  Consider using Martin's 3D-printed HP-IL connectors.

Where would I find those? 3D Printing the connector housing seems a good idea, but are contacts available that fit?

Cheers,
Harald
02-21-2018, 10:05 AM
Post: #15
 Didier Lachieze Senior Member Posts: 1,427 Joined: Dec 2013
RE: Longer HP-IL cable runs
All details are documented on this page from Martin.
02-21-2018, 10:28 AM
Post: #16
 Harald Senior Member Posts: 757 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-21-2018 10:05 AM)Didier Lachieze Wrote:  All details are documented on this page from Martin.

Thank you, that is very helpfull!
02-21-2018, 04:31 PM
Post: #17
 Dave Frederickson Senior Member Posts: 2,118 Joined: Dec 2013
RE: Longer HP-IL cable runs
(02-21-2018 10:01 AM)Harald Wrote:
(02-16-2018 09:13 PM)Dave Frederickson Wrote:  Consider using Martin's 3D-printed HP-IL connectors.

Where would I find those? 3D Printing the connector housing seems a good idea, but are contacts available that fit?

Cheers,
Harald

The connector housings are available on Shapeways.

https://www.shapeways.com/product/XTCXFV...d=64602806
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