#19254 - 01/15/08 06:11 AM
75176 com chip
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petec
active contributor
Registered: 02/05/03
Posts: 167
Loc: Hyde Park, NY
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looking around for replacemnet com chips I came across two items from Texas Instruments, SN75176AP and SN75176BP, both about $.55, and two from National Semi, DS75176BN/NOPB and DS75176BTN/NOPB, both about $1.70 . . (all at Digi-Key.com)
anybody know what the differences are ? ?
what one does ADI use (OE) ? ?
is there any reason not to go w/ the cheap ones from TI ? ?
TIA
Pete C
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#19255 - 01/15/08 06:15 AM
Re: 75176 com chip
[Re: petec]
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ADI Tech Support
addict
Registered: 12/22/02
Posts: 622
Loc: Branson West, MO
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We use the TI 75176BP.
Kevin Barrett
ADI Tech Support
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#19256 - 01/15/08 06:18 AM
Re: 75176 com chip
[Re: ADI Tech Support]
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petec
active contributor
Registered: 02/05/03
Posts: 167
Loc: Hyde Park, NY
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Kevin,
I'll go with that . . thanks for the quick reply . .
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#19361 - 01/25/08 10:17 AM
Re: 75176 com chip
[Re: petec]
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TCoupe
newbie
Registered: 01/25/08
Posts: 6
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I'm sending in my SECU-16 I/O unit because the comm LED is stuck on (red). Could it be fixed by simply changing the 75176BP chip? If so, where do you get chips?
~Terry
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#19365 - 01/26/08 05:12 PM
temperature measurement
[Re: Guy Lavoie]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Just joining your forum.
First time for a post. Hope I do it correctly.
I have recently purchased an ocelot and SECU16
My problem is trying to get the unit to track room temperature.
I want to use a thermistor as the sensing unit because of the
number of points I want to measure(about 25). Using a Bobcat for
each of these points would be quite costly.
I first of all used a thermistor from junk box and got the program working. I had a reading using the debug timer & variable. With that working, I purchased a thermistor from
Mouser. Once installed, my problem became evident. The reading
wants to stay around 70 degrees. Room temperature at night
drops to 62, but unit will stay at 70 or maybe 69 degrees.
If I take hold of unit, the heat from my fingers will make
reading go to 75 or if I put the sensor outside where the
temperature is about 30, the reading will start dropping
about 1 degree every two minutes.
I have even brought home a commercial sensor from work and
get about the same results.
My physical connections consist of a 1K precision resistor
in place of the shorting jumper and a 10K precision in series
with the thermistor from input on the SECU16 to ground.
The thermistor is a 10K unit. My input return a value of 233.
At this point, I seem to be lost as to the next move.
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#19384 - 01/29/08 05:23 PM
Re: temperature measurement
[Re: Guy Lavoie]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Thank you Guy for your reply
In regards to the resistor in series,
I was going off of a post from JeffVolp
on 6/5/05 #12047
Will get some readings and let you know
Leonard
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#19390 - 01/29/08 09:03 PM
Re: temperature measurement
[Re: JeffVolp]
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jwilson56
journeyman
Registered: 04/09/04
Posts: 53
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My personal experience with using thermistor is that they are not very good for accurate temperature measurements. Maybe for over temp alarms, ect.
Twelve LM34's came with my the Ocelot stuff I bought but I use 1-wire for temps. From what I have seen a lot of people are using the LM34 with the SECU-16 and they are relatively cheap.
John
Edited by jwilson56 (01/29/08 09:05 PM)
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#19404 - 01/30/08 07:22 PM
Re: temperature measurement
[Re: JeffVolp]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Thanks guys for your input
Due to the problem with LM34 and length of wire
I would prefer to stay with the thermistor
Jeff, I tried to find the RL503 10K thermistor
you referenced in your post
Mouser is out of stock & won't have shipment
until middle of March
I do have stock# 594-NTCLE100E3103HBO from Mouser
It is a 10K
Can this be made to work
Physical wiring:
I have a 1K precision resistor in place of the
shorting pin
The resistor is across the pins for
the supervised setting
The thermistor is wired from input to ground
I removed the 10K in series with the thirmistor
Test results:
I have a digital thermometer setting next to the
thermistor
Voltage is across input & ground at SECU16
The reading is C-Max program reading LOAD DATA
into varible then monitored on debug variables
Voltage Temperature Reading
4.27 73.0 217
4.28 72.5 217
4.29 72.0 218
4.30 71.6 218
4.31 71.1 218
4.32 69.6 219
4.33 68.7 219
4.34 68.0 219
4.35 67.8 219
4.36 67.1 220
4.37 66.7 221
4.38 66.2 221
This data was recorded as the temperature fell
in the control space.
As the temperature was brought back up, the
reading and the voltage did not stay together.
For example, when the reading changed from
220 to 219, the voltage was 4.33
Why doesn't the voltage & reading stay together?
Thanks Jeff for any help you can give
Leonard
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#19406 - 01/30/08 08:40 PM
Re: temperature measurement
[Re: lpayne]
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JeffVolp
active contributor
Registered: 01/26/03
Posts: 177
Loc: St. George, Utah
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As I said earlier, even though it is a 10K thermistor, it may not have the same temperature characteristics. To check, download the data sheets for each one and compare the resistance readings over the range of interest. If they are similar, then you can use the equations in that earlier post. If not, you have to plot the voltage divider curve, and recalculate the coefficients.
However, that is not your main problem. The 10K precision resistor goes inside the SECU16 in place of the shorting jumper (in the supervised position). That is added in series with the 1K pull-up to 5V which is already wired to one side of the jumper, giving a total of 11K. Now you just have 2K, which is why the voltage readings are so high.
Regarding the match between the A/D reading and the voltage reading, you are limited by the maximum resolution of the A/D converter. If you change the "jumper" resistor to 10K 1%, the A/D resolution per degree will increase by a factor of 5.
Obviously, when the temperature is half way between two values, the reading can jump back and forth just like the readout on any digital thermometer.
Jeff
_________________________
X-10 automation since the BSR days
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#19425 - 02/01/08 03:34 AM
Re: temperature measurement
[Re: JeffVolp]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Thank you Jeff
Now I understand what you are saying
I will get a 10K & gev it a try
Leonard
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#19437 - 02/02/08 08:33 PM
Re: temperature measurement
[Re: lpayne]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Jeff
Tried the 10K
Unit tracks quite well
I just used a 20% resistor from junk box
Was surprised how well it did
Have ordered precision resistors from Mouser
Have also ordered the Molex connector
Thanks again for setting me straight
I reread your 05 post & saw where I misunderstood
Talk to you latter as project comes together
Leonard
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#22478 - 04/23/11 10:14 AM
pump remote control
[Re: petec]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Need to monitor and control pumps at a camp
Will put Ocelot at one location
The other two locations are about 600' away in
different directions
Will use cat5e aerial cable to communicate
with modules.
Has anyone had similar experience with contolling
modules over long distance
Any help would be appreciated
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#22480 - 04/23/11 10:30 AM
Re: pump remote control
[Re: lpayne]
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ADI Tech Support
addict
Registered: 12/22/02
Posts: 622
Loc: Branson West, MO
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You can use an Ocelot, a SECU16 or SECU16I (for the inputs) along with a RLY8XA to control the pumps. The Ocelot connects to the SECU16, SECU16I and RLY8XA using CAT5, and run up to 4000 feet. I recommend using the RLY8XA to control the pumps because the relays can switch up to 240V at 5 amps, as apposed to the relays on the SECU16 that can only switch 24VDC.
Kevin Barrett
ADI Tech Support
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#22482 - 04/23/11 11:05 AM
Re: pump remote control
[Re: Guy Lavoie]
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lpayne
newbie
Registered: 01/26/08
Posts: 7
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Thanks for information
I understand the problem with aerial cable
If I put lightning arrestors on each line & and
each end, would that solve the problem?
How does phone company protect their equipment?
Direct burial cable would be difficult because
of the terrain and access roads
If I do use cat5e, can the com line leave the ocelot
and go in 3 different directions
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#22483 - 04/23/11 11:07 AM
Re: pump remote control
[Re: Guy Lavoie]
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ADI Tech Support
addict
Registered: 12/22/02
Posts: 622
Loc: Branson West, MO
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The wireless modules (G2 Access Points) that can connect the Ocelot to the modules have a range of 300 feet. That is why I did not suggest them.
Kevin Barrett
ADI Tech Support
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