I third the Railroad Museum. Only 2 hours driving from San Jose and half an hour or so from Parallax. And if you're not driving: the railroad museum is right next to the Amtrak station...
By the way "old town Sacramento" means the restored remains of the oldest part of Sacramento that was first built in the 1920s and restored in the 1970s or 1980s. "Old" means something totally different in the United States than in Europe. Where I come from, a 19th century church or windmill is hardly worth a second look because there are so many of them. Here, everything older than 50 years is regarded as ancient :-)
And while you're in Sacramento, the State Capitol building (not far from Old Sac) may also be worth a visit. It should look somewhat familiar if you've ever seen pictures of Washington DC (I think it's a replica). The trees in front of it are just as impressive as the building itself.
Wow guys, lot's more great suggestions coming. I'm really rushed with the work load here. Hope I can get the job done and make some free time.
Can't believe I climbed up a vertical aluminium ladder to the roof of a warehouse to survey our installation site yesterday. That's more meters up than I like to think about. I'm definitely not insured for it.
Anyone know where to source some nice RS485 cable? Around here?
We have some cable here but it's not ideal. It's not what I spec'ed out before I got here. If it does not work I'm going to need to find:
400ft of 4 or 6 core cable. That's 2 or 3 twisted pairs, suitable for RS485.
This has cable has to carry a half duplex data connection + and -. And it has to carry power and ground.
Power consumption is only watts and we can drive it from 10 to 24 volts so voltage drop should not be an issue.
There are installations where I just use 4-core phone cable for just that purpose including 24V supply. Surely everyone sells phone cable and if it's good enough for telcos it must be good enough for this.
I have to get RS485 half duplex, point to point, at 115200 baud over a distance of 400ft.
My gut tells me it will work. My gut knows that in the past I have rolled out hundreds of DSL connections at 768Kilo Baud over city owned telephone cables all round Scandinavia.
It's worries me because I have not done this particular thing before. And it turns out the distance is a lot more than I was told it would be. The DSL thing we had tested with kilometres of cable prior to roll out. (We even demoed it running over lengths of barbed wire fence!)
On the other hand the cable they have here is not even twisted pair.
The power drop should not be an issue. The thing runs over a wide voltage range so if there is voltage drop we can just shove more in the other end.
Anyway, the contractors are coming tomorrow to install and pull the cable. So we will see what happens.
If does not work I could be stuck here until it does
I have to get RS485 half duplex, point to point, at 115200 baud over a distance of 400ft.
My gut tells me it will work. My gut knows that in the past I have rolled out hundreds of DSL connections at 768Kilo Baud over city owned telephone cables all round Scandinavia.
It's worries me because I have not done this particular thing before. And it turns out the distance is a lot more than I was told it would be. The DSL thing we had tested with kilometres of cable prior to roll out. (We even demoed it running over lengths of barbed wire fence!)
On the other hand the cable they have here is not even twisted pair.
The power drop should not be an issue. The thing runs over a wide voltage range so if there is voltage drop we can just shove more in the other end.
Anyway, the contractors are coming tomorrow to install and pull the cable. So we will see what happens.
If does not work I could be stuck here until it does
Barbed wire? Well I have used plain old figure eight fireproof cable in high-rise lift shafts that snaked up and down and around through about 10 lifts over 20 something floors IIRC because that was all I had and I didn't have a choice. So I ran RS485 at 19.2k baud over those lines and it all worked reliably. So I figure that "only" 400' of whatever cable you have will work fine for 115k which is still fairly slow for RS485 anyway. But my best recommendation is 4-core phone cable as it is a lot easier to work with and more flexible than CAT5 but both these are as common as mud.
Not that it would be so terrible to be stuck here for another week or two
The barbed wire thing was a stunt pulled by a sales guy at some expo or other where they were showing off our DSL solution.
That was a great project. Each node was a Linux embedded system with 4 DLS ports, Ethernet, serial etc. The nodes were redundantly connected across whole cities. Any failures in nodes or connections were routed around automatically by the OSPF routing protocol.
All in the name of upgrading their existing networks that ran some proprietary serial protocol at 1200 baud.
I have to get RS485 half duplex, point to point, at 115200 baud over a distance of 400ft.
...
On the other hand the cable they have here is not even twisted pair.
If that cable is not already run, best to upgrade to at least differential.
If you need power, and it does not need armoring or anything special, CAT5 should give ok power.
How much current, and what is the ground tolerance on this ?
ie is the remote end powered and connected only to the master end ?
Oh yeah, funny that sparkies never think that there is anything wrong with running "data" cable alongside masses of 3-phase cables for long distances because all the channels and conduits are already there! Then they look at you all strange when you are gesturing and lost for words before them!
The unit at the far end only consumes 4 Watts when run from 12 volts. It's just point to point. The remote end connects to nothing else. Except perhaps ground via whatever support it is bolted to. I forget now if the circuitry is actually connected to it's chassis.
I was once called over to find out why Unit A connected to Unit B over RS485 in the same cabinet always resulted in the drivers of one unit being totally blown. Turned out that one unit's ground was flying up and down by 60 volts w.r.t. the other!
As far as I can tell, from climbing the roof and looking over the proposed routing of the cable it's not passing by anything excessively interference producing. Most of it is far away from even the building's electrical cables.
It's not as if this was a factory or machine shop.
The contractors seemed to be pretty savvy. Perhaps if tell them to keep it away from other circuits they will get the idea.
Oh yeah, funny that sparkies never think that there is anything wrong with running "data" cable alongside masses of 3-phase cables for long distances because all the channels and conduits are already there! Then they look at you all strange when you are gesturing and lost for words before them!
Oh boy! I've been in that very situation at an (unnamed) fruit-packing plant. The RS422 shielded, twisted-pair cable ran alongside 440V conveyor power in the same conduit. It just didn't work.
Well, I forget the figures exactly but I measure the current consumption on a 12 volt supply and arrived at a power consumption of 3.5Watts. A bit less than the 4 Watts in the specification.
Allied Electronics
6830 Via Del Oro
Suite 100
San Jose CA 95119
Phone 408-226-7008
Fax: 408-226-7010 http://www.alliedelec.com
1X Technologies - San Jose
San Jose, CA 95123
(307) 256-7849
HSC Electronic Supply (Halted is also a place worth visiting - Steve Jobs bought stuff from them in the 1970's in their previous location)
3051 Corvin Dr
Santa Clara.
1-800-4-HALTED http://www.halted.com/
Oh yeah, funny that sparkies never think that there is anything wrong with running "data" cable alongside masses of 3-phase cables for long distances because all the channels and conduits are already there! Then they look at you all strange when you are gesturing and lost for words before them!
Oh boy! I've been in that very situation at an (unnamed) fruit-packing plant. The RS422 shielded, twisted-pair cable ran alongside 440V conveyor power in the same conduit. It just didn't work.
They usually do have a clue about such things but prefer not to bring it up if it wasn't specified. Good for the extra work later.
I'm curious as to what your Google search terms were that returned such bizarre results?
Anyway, pink is OK in small doses. Poodles on the other hand.....
Would I suffer both at the same time for a cigarette? Not sure.
As it is the local bar here has a terrace where you are free to smoke. Nobody does except me.
Note: I am not defending smoking in any way. Terrible habit that it is.
It is kind of a long story that I have to carefully tell in light of the fact that we are on a PG-13 forum.
First, I should apologize to Google... in truth, I was speaking to Google using voice recognition, without my teeth, using Win10.
So, the error could be anywhere in that technical mix.
I said to Google: "Feynman... serial communications" Google thought I said "Feynman...cereal communications." and pointed me
to the first link above... which had a story (wink, wink) about Feynman visiting strip malls (In the USofA,
we call small shopping centers "strip malls.") Anyway there is a story in that link about Feynman visiting "strip malls" on
almost a daily basis because it helped him think deep thoughts. As a diversion, he was particularly fond of throwing fruit loops
at the employees and occasionally one of the fruit loops would completely disappear... this was apparently the inspiration for QED theory.
So, naturally I wondered if there was any history of Feynman visiting San Jose... So I told Google: "San Jose, Feynman, fruit loops, strip malls"
and I hit the jackpot.
Kind of makes you wonder if somewhere deep down inside, Feynman saw some moral equivalence between his role in physics and being an employee of a strip mall. He has been rewarded handsomely. Don't you think?
Comments
I second the railroad museum. At that point you're in the heart of Old Town Sacramento.
By the way "old town Sacramento" means the restored remains of the oldest part of Sacramento that was first built in the 1920s and restored in the 1970s or 1980s. "Old" means something totally different in the United States than in Europe. Where I come from, a 19th century church or windmill is hardly worth a second look because there are so many of them. Here, everything older than 50 years is regarded as ancient :-)
And while you're in Sacramento, the State Capitol building (not far from Old Sac) may also be worth a visit. It should look somewhat familiar if you've ever seen pictures of Washington DC (I think it's a replica). The trees in front of it are just as impressive as the building itself.
===Jac
Can't believe I climbed up a vertical aluminium ladder to the roof of a warehouse to survey our installation site yesterday. That's more meters up than I like to think about. I'm definitely not insured for it.
We have some cable here but it's not ideal. It's not what I spec'ed out before I got here. If it does not work I'm going to need to find:
400ft of 4 or 6 core cable. That's 2 or 3 twisted pairs, suitable for RS485.
This has cable has to carry a half duplex data connection + and -. And it has to carry power and ground.
Power consumption is only watts and we can drive it from 10 to 24 volts so voltage drop should not be an issue.
There are installations where I just use 4-core phone cable for just that purpose including 24V supply. Surely everyone sells phone cable and if it's good enough for telcos it must be good enough for this.
What is wrong with the cable you have already ?
The most widely available cable will be CAT5 ?
My gut tells me it will work. My gut knows that in the past I have rolled out hundreds of DSL connections at 768Kilo Baud over city owned telephone cables all round Scandinavia.
It's worries me because I have not done this particular thing before. And it turns out the distance is a lot more than I was told it would be. The DSL thing we had tested with kilometres of cable prior to roll out. (We even demoed it running over lengths of barbed wire fence!)
On the other hand the cable they have here is not even twisted pair.
The power drop should not be an issue. The thing runs over a wide voltage range so if there is voltage drop we can just shove more in the other end.
Anyway, the contractors are coming tomorrow to install and pull the cable. So we will see what happens.
If does not work I could be stuck here until it does
I have tested both cat5 ( to 1000 feet ) and phone cable ( to 680 feet ) for RS485 & power up to 230K with no errors.
Barbed wire? Well I have used plain old figure eight fireproof cable in high-rise lift shafts that snaked up and down and around through about 10 lifts over 20 something floors IIRC because that was all I had and I didn't have a choice. So I ran RS485 at 19.2k baud over those lines and it all worked reliably. So I figure that "only" 400' of whatever cable you have will work fine for 115k which is still fairly slow for RS485 anyway. But my best recommendation is 4-core phone cable as it is a lot easier to work with and more flexible than CAT5 but both these are as common as mud.
Not that it would be so terrible to be stuck here for another week or two
The barbed wire thing was a stunt pulled by a sales guy at some expo or other where they were showing off our DSL solution.
That was a great project. Each node was a Linux embedded system with 4 DLS ports, Ethernet, serial etc. The nodes were redundantly connected across whole cities. Any failures in nodes or connections were routed around automatically by the OSPF routing protocol.
All in the name of upgrading their existing networks that ran some proprietary serial protocol at 1200 baud.
If that cable is not already run, best to upgrade to at least differential.
If you need power, and it does not need armoring or anything special, CAT5 should give ok power.
How much current, and what is the ground tolerance on this ?
ie is the remote end powered and connected only to the master end ?
Also, what else is the cable being run next to ?
Oh yeah, funny that sparkies never think that there is anything wrong with running "data" cable alongside masses of 3-phase cables for long distances because all the channels and conduits are already there! Then they look at you all strange when you are gesturing and lost for words before them!
You are worrying me again...
The unit at the far end only consumes 4 Watts when run from 12 volts. It's just point to point. The remote end connects to nothing else. Except perhaps ground via whatever support it is bolted to. I forget now if the circuitry is actually connected to it's chassis.
I was once called over to find out why Unit A connected to Unit B over RS485 in the same cabinet always resulted in the drivers of one unit being totally blown. Turned out that one unit's ground was flying up and down by 60 volts w.r.t. the other!
As far as I can tell, from climbing the roof and looking over the proposed routing of the cable it's not passing by anything excessively interference producing. Most of it is far away from even the building's electrical cables.
It's not as if this was a factory or machine shop.
The contractors seemed to be pretty savvy. Perhaps if tell them to keep it away from other circuits they will get the idea.
I get just under 7 volts loop drop at 4 watts/12v nominal, over 400 feet.
Quite a bit...
-Phil
What cable are you basing that voltage drop calculation on?
Heck, in the morning I'm going to measure the resistance of what we have here.
Just an idle google, that pops up this, amongst others..
Cat5 wire gauge is usually 24 AWG which would be 2.567 ohms per 100 feet.
18 guage wire. (Yeah, that's what we got here)
13.5 Volts in at one end (Happens to be the supply we have here.)
400 ft
0.5 amp load
Results in a drop of 2.5 volts
13.5 - 2.5 = 11 volts
This thing runs from 10 volts.
Hmm....
We can go higher on the supply voltage if need be.
Here are a few local distributors worth calling:
Allied Electronics
6830 Via Del Oro
Suite 100
San Jose CA 95119
Phone 408-226-7008
Fax: 408-226-7010
http://www.alliedelec.com
1X Technologies - San Jose
San Jose, CA 95123
(307) 256-7849
HSC Electronic Supply (Halted is also a place worth visiting - Steve Jobs bought stuff from them in the 1970's in their previous location)
3051 Corvin Dr
Santa Clara.
1-800-4-HALTED
http://www.halted.com/
Jeff
Remember your roots.
Close your eyes. Ask yourself ... what would Richard Feynman do?
uncyclopedia.wikia.com/wiki/Richard_Feynman
I put the issue to Google... here's what I got.
No way am I going anywhere near a bar called the "Pink Poodle".
Anyway, pink is OK in small doses. Poodles on the other hand.....
Would I suffer both at the same time for a cigarette? Not sure.
As it is the local bar here has a terrace where you are free to smoke. Nobody does except me.
Note: I am not defending smoking in any way. Terrible habit that it is.
It is kind of a long story that I have to carefully tell in light of the fact that we are on a PG-13 forum.
First, I should apologize to Google... in truth, I was speaking to Google using voice recognition, without my teeth, using Win10.
So, the error could be anywhere in that technical mix.
I said to Google: "Feynman... serial communications" Google thought I said "Feynman...cereal communications." and pointed me
to the first link above... which had a story (wink, wink) about Feynman visiting strip malls (In the USofA,
we call small shopping centers "strip malls.") Anyway there is a story in that link about Feynman visiting "strip malls" on
almost a daily basis because it helped him think deep thoughts. As a diversion, he was particularly fond of throwing fruit loops
at the employees and occasionally one of the fruit loops would completely disappear... this was apparently the inspiration for QED theory.
So, naturally I wondered if there was any history of Feynman visiting San Jose... So I told Google: "San Jose, Feynman, fruit loops, strip malls"
and I hit the jackpot.