Re: [Owfs-developers] Reading latesttemp
Just looked at it again and all sensors are now reading correctly, so I am wondering if there was a bad connection somewhere. As they are all working I will try to see if I can recreate the problem, but not sure I will be able to. I'll get back to you if I discover anything further. Thanks Mick On 08/10/2020 19:47, Mick Sulley wrote: This is a test setup, all sensors are in a breadboard on the bench, power is from a Meanwell unit set to 5.1 volts, which is what I measure at the sensors. So I am pretty confident it is not a wiring or power supply problem. Is there any way to determine if the simultaneous command is getting to all of the chips? I am pretty confident that if I power cycle it all the problem will go away and I won't be able to recreate it, so I am trying to investigate as much as I can while the situation exists. Thanks Mick On 08/10/2020 17:27, Jan Kandziora wrote: Am 08.10.20 um 15:07 schrieb Mick Sulley: But owwrite /simultaneous/temperature 1 should trigger a conversion? and reading latesttemp should then be correct. Here is another. Latesttemp returns 85 even after owwrite /simultaneous/temperature 1, but read temperature12 and it works again. I don't understand why! Most likely it's a problem with power. Do you power each chip separately, or do they all pull, from the same +5V line? I have a few more in this state at the moment, I am sure I could fix them all with a single temperature12 read to each and they would then be fine, but I would really like to understand what the problem is You could try to find out if the simultaneous command is not going through to all chips (chips never read 85°C on latesttemp) or if you still get those spurious resets. But it's only a debugging tool. In a production setup, it would only ever mask the underlying problem and return a wrong ages-old temperature instead. Kind regards Jan ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
Re: [Owfs-developers] Reading latesttemp
This is a test setup, all sensors are in a breadboard on the bench, power is from a Meanwell unit set to 5.1 volts, which is what I measure at the sensors. So I am pretty confident it is not a wiring or power supply problem. Is there any way to determine if the simultaneous command is getting to all of the chips? I am pretty confident that if I power cycle it all the problem will go away and I won't be able to recreate it, so I am trying to investigate as much as I can while the situation exists. Thanks Mick On 08/10/2020 17:27, Jan Kandziora wrote: Am 08.10.20 um 15:07 schrieb Mick Sulley: But owwrite /simultaneous/temperature 1 should trigger a conversion? and reading latesttemp should then be correct. Here is another. Latesttemp returns 85 even after owwrite /simultaneous/temperature 1, but read temperature12 and it works again. I don't understand why! Most likely it's a problem with power. Do you power each chip separately, or do they all pull, from the same +5V line? I have a few more in this state at the moment, I am sure I could fix them all with a single temperature12 read to each and they would then be fine, but I would really like to understand what the problem is You could try to find out if the simultaneous command is not going through to all chips (chips never read 85°C on latesttemp) or if you still get those spurious resets. But it's only a debugging tool. In a production setup, it would only ever mask the underlying problem and return a wrong ages-old temperature instead. Kind regards Jan ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
Re: [Owfs-developers] Reading latesttemp
Am 08.10.20 um 15:07 schrieb Mick Sulley: > > But owwrite /simultaneous/temperature 1 should trigger a conversion? and > reading latesttemp should then be correct. Here is another. Latesttemp > returns 85 even after owwrite /simultaneous/temperature 1, but read > temperature12 and it works again. I don't understand why! > Most likely it's a problem with power. Do you power each chip separately, or do they all pull, from the same +5V line? > > I have a few more in this state at the moment, I am sure I could fix > them all with a single temperature12 read to each and they would then be > fine, but I would really like to understand what the problem is > You could try to find out if the simultaneous command is not going through to all chips (chips never read 85°C on latesttemp) or if you still get those spurious resets. But it's only a debugging tool. In a production setup, it would only ever mask the underlying problem and return a wrong ages-old temperature instead. Kind regards Jan ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
Re: [Owfs-developers] Reading latesttemp
On 08/10/2020 12:26, Jan Kandziora wrote: Am 08.10.20 um 00:31 schrieb Mick Sulley: On my test system I have 20 DS18B20 temperature sensors (all powered) to test out various things. I am setting /simultaneous/temperature waiting 2 seconds then reading latesttemp from all of them. I have just noticed that several are giving 85 reads. If I look with owhttpd this is what I see - owhttpd screen Also owread /uncached/DHW_Mid_Btm/latesttemp returns 85. This is after many cycles of simultaneous/voltage and latesttemp reads. Reading /uncached//latesttemp reads the contents of the temperature register from the chip. It never triggers a temperature conversion. But owwrite /simultaneous/temperature 1 should trigger a conversion? and reading latesttemp should then be correct. Here is another. Latesttemp returns 85 even after owwrite /simultaneous/temperature 1, but read temperature12 and it works again. I don't understand why! pi@pi4b:~ $ owread /DHW_Top/latesttemp 85pi@pi4b:~ $ owread /DHW_Top/latesttemp 85 pi@pi4b:~ $ owwrite /simultaneous/temperature 1 pi@pi4b:~ $ owread /DHW_Top/latesttemp 85pi@pi4b:~ $ owread /DHW_Top/latesttemp 85pi@pi4b:~ $ pi@pi4b:~ $ owread /DHW_Top/temperature12 13.5625pi@pi4b:~ $ owread /DHW_Top/latesttemp 13.5625pi@pi4b:~ $ pi@pi4b:~ $ I have a few more in this state at the moment, I am sure I could fix them all with a single temperature12 read to each and they would then be fine, but I would really like to understand what the problem is If you read 85°C from latesttemp, it means the latest conversion either 85°C (unlikely) or the chip has been power-cycled since the latest conversion (likely). As 85°C is the power-on value of that register. It seems to me that it is a useful safeguard to run a single temperature12 read on each sensor during the initialisation of the system. I cannot see any downside to this but just thought I would ask for your thoughts. That doesn't make any sense as you will read back the value from that initial conversion again and again if your simultaneous trigger isn't working. You mask the error that way, which is likely not what you want. If a sensor reports a spurious 85°C, treat that as a power-cycle on that sensor – check your hardware! Kind regards Jan ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
Re: [Owfs-developers] Reading latesttemp
Am 08.10.20 um 00:31 schrieb Mick Sulley: > On my test system I have 20 DS18B20 temperature sensors (all powered) to > test out various things. I am setting /simultaneous/temperature waiting > 2 seconds then reading latesttemp from all of them. > > I have just noticed that several are giving 85 reads. If I look with > owhttpd this is what I see - > > owhttpd screen > > Also owread /uncached/DHW_Mid_Btm/latesttemp returns 85. This is after > many cycles of simultaneous/voltage and latesttemp reads. > Reading /uncached//latesttemp reads the contents of the temperature register from the chip. It never triggers a temperature conversion. If you read 85°C from latesttemp, it means the latest conversion either 85°C (unlikely) or the chip has been power-cycled since the latest conversion (likely). As 85°C is the power-on value of that register. > > It seems to me that it is a useful safeguard to run a single > temperature12 read on each sensor during the initialisation of the > system. I cannot see any downside to this but just thought I would ask > for your thoughts. > That doesn't make any sense as you will read back the value from that initial conversion again and again if your simultaneous trigger isn't working. You mask the error that way, which is likely not what you want. If a sensor reports a spurious 85°C, treat that as a power-cycle on that sensor – check your hardware! Kind regards Jan ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
[Owfs-developers] Reading latesttemp
On my test system I have 20 DS18B20 temperature sensors (all powered) to test out various things. I am setting /simultaneous/temperature waiting 2 seconds then reading latesttemp from all of them. I have just noticed that several are giving 85 reads. If I look with owhttpd this is what I see - owhttpd screen Also owread /uncached/DHW_Mid_Btm/latesttemp returns 85. This is after many cycles of simultaneous/voltage and latesttemp reads. However if I run owread /uncached/DHW_Mid_Btm/temperature12 it returns 13.4375. If I then owread /uncached/DHW_Mid_Btm/latesttemp it also returns 13.4375 and after that it seems to work as expected. So it seems that reading temperature12 resets it. I can't reproduce this, as I say, once a temperature12 read resets it it works fine. It seems to me that it is a useful safeguard to run a single temperature12 read on each sensor during the initialisation of the system. I cannot see any downside to this but just thought I would ask for your thoughts. Thanks Mick ___ Owfs-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/owfs-developers
