XBee S1/XBee Pro S1 substuitiion
jruthroff
Posts: 38
I've a project that uses a SHT11 temp/humidity sensor, a BS2 and an XBee S1 to send the temp/humidity data to a "base" unit, where another Xbee S1/BS2 combo processes that data and sends it to some 7 segement LED displays via a Maxim 7219. For testing purposes, the remote unit sends the data about every 10 seconds or so. When it's finished, I'll probably slow that down to about once a minute.
I've decided that I would like to transmitter to have a little more range than it does. It's mounted just outside the house, and I'd like to have a remote unit inside the house but at the far side. The XBee S1 falls a bit short on able to reach that far, so I thought the Xb11 S1 Pro unit might do the trick. And it does, but my problem is that the Pro unit consistently stops transmitting about 15 minutes after it's powered-up. This only happens when a "Pro" is doing the transmitting. I can swap the "Pro" and standard units in the receiver and both work well. But if I put a Pro unit in the transmitter the data stops flowing at about 15 minutes. When I stick a standard transmitter back in it'll transmit for days. If I take the Pro unit that failed in the transmitter and put it in the receiver, it'll receive for days. I've done this swap about 10 times now, and the results are consistent.
The "Getting Started with XBee RF Modules" indicates that the Standard S1 and Pro S1 modules are "nearly identical in operation and function", the only difference being size and power consumption/output. The pinouts are the same. I've not read where adjusting code is requirered when using the Pro units.
It seems highly unlikely that I have two bad Pro units, but I suppose it's possible.
Ideas/comments?
Thanks!
John
temp receiver new.bs2
I've decided that I would like to transmitter to have a little more range than it does. It's mounted just outside the house, and I'd like to have a remote unit inside the house but at the far side. The XBee S1 falls a bit short on able to reach that far, so I thought the Xb11 S1 Pro unit might do the trick. And it does, but my problem is that the Pro unit consistently stops transmitting about 15 minutes after it's powered-up. This only happens when a "Pro" is doing the transmitting. I can swap the "Pro" and standard units in the receiver and both work well. But if I put a Pro unit in the transmitter the data stops flowing at about 15 minutes. When I stick a standard transmitter back in it'll transmit for days. If I take the Pro unit that failed in the transmitter and put it in the receiver, it'll receive for days. I've done this swap about 10 times now, and the results are consistent.
The "Getting Started with XBee RF Modules" indicates that the Standard S1 and Pro S1 modules are "nearly identical in operation and function", the only difference being size and power consumption/output. The pinouts are the same. I've not read where adjusting code is requirered when using the Pro units.
It seems highly unlikely that I have two bad Pro units, but I suppose it's possible.
Ideas/comments?
Thanks!
John
temp receiver new.bs2
Comments
Secondly, the regulator that you are using (3.3V) to power the XBee, what type of dropout voltage does it have? The XBee pro's draw a considerable amount more power than the the regular Series 1 XBee's. I ask just to rule out that the Vreg, or power supply isn't dropping down below that of dropout voltage after this time interval. This would cause the XBee Pro to not transmitt properly after an x amount of power draw time.? I would also make sure your sleep mode on the PRO is configured properly for your system.
All this is mounted on a Parallax Board of Education for prototyping purposes, and power is supplied by the on-the-board regulator. I'll have to find out its drop out voltage.
Concerning the sleep mode, I'll have to look into that. I use the two XBee Pros out of the box (no configuration changes) so I'll have to confirm their out of the box settings. I'll report back when I do.
Thanks again,
John
The receivere is a Parallax BOE, powered by a Parallax 7.5v volt, 1amp wall wart power supply. It has a BS2, a Maxim 7219, two seven segement LED displays, and a XBee USB Adaptor Board.
Nothing is (or has been) running off batteries.
I did bump the XBee Pro power down from "Highest" to "High" (problem persists), and then tested it at "Lowest". Again, the problem persists...about 16 minutes after power-up the transmission stops.
I still need to check/update the firmware on the Pro units.
Thanks for any ideas!
John
Just a thought to check. I would also make sure that both PRO units have the same version of software too.
1). Transmitter with an XBee Pro.
2). Receiver with the LED displays with a standard XBee.
3). An XBee Pro hooked via USB to a PC using X-CTU to watch the data stream.
After about 16 minutes, data ceased to flow to the receiver and to the X-CTU utility. I'm repeating this experiment twice and got the same results. This seems to imply that something the receiver is doing is causing the transmitter to shut down. When I alter the setup so that a standard XBee is doing the transmitting (changing nothing else), there is no interruption in the data flow.
Very confusing!
John
transmit.docBoth units did have firmware 10E6. I upgraded them both to 10E8. Testing with the new firmware gives the same results...data flow stops at about 16 minutes.
I began to wonder if the wiring on my transmitter board might be causing some issue. So I set the XBee up on a BOE, but left out the temp/humidity sensor, so basically this was a BOE with a BS2 and XBee on it. I ran the same code, but substituted constant values for the temp and humidity so it would have something to transmit. Again, with a standard XBee transmitting to another standard XBee or an XBee Pro, there were no problems. When I plugged the XBPro into the transmitter, data flow stopped at about 16 minutes.
I'm trying to think of what else I can do to narrow this down.
John
Forgot receive.doc, here it is.
First, apart from the power there should be no difference between the regular XBee and the PRO. Certainly in my small network they interwork perfectly happily. I also monitor the Digi forums because I wrote and maintain the XBee 802.15.4 cookbook and FAQ there (mentioned in this forum in a recent post by Kevin Cook), and I can tell you that I haven't seen any reports there of incompatibilities.
Looking at your receive.pro and transmit.pro files, they are byte-for-byte identical. I wouldn't have expected to see that. What I would expect would be that of the two communicating modules, each would have its destination address equal to the source address of the other. That can be done using 64-bit addressing (MY=0xfffe, DH=other SH, DL=other SL) or 16-bit addressing (see product manual or cookbook).
What you seem to have is a situation where all modules have the same address. It's interesting that you were able to use a third module to monitor the other two, but also worrying. Consider this:
- There are two addressing modes with XBees: unicast and broadcast.
- In unicast mode one XBee sends something to one specific other XBee. No other XBee will receive the transmission. In unicast mode, transmissions will be acknowledged. If not acknowledged they'll be re-sent.
- In broadcast mode one XBee sends something to all other XBees on its channel and PANID. No acknowledgements will be sent, so broadcast mode gives no promise of a successful communication.
By using identical addresses in your monitoring experiment you seem to have achieved what I'd have imagined was impossible: a unicast transmission received by two separate XBees. But it must come at a price: if one receives it and the other doesn't, whichever does receive it will send an acknowledgement and the original sender will believe it got through. That seems to break the idea of reliable communication.
So my suggestions would be:
1. Set up each XBee to talk directly to the other. Easiest way is to set MY=0xfffe in each case, and at both ends set DH to the other's SH, and DL to the other's SL.
2. If that doesn't help, consider another possibility. Your XBees are still using the default channel and PANID. Is it possible that there are other XBees in your vicinity that are also still using the defaults, and perhaps adding to the confusion?
I looked at your profiles and agree with johnfos. You have the same address in both ends. If I understand your project correctly, the reason you are using the PRO module is because of the further distance. Since you only have 1 of those modules, make that the transmitter module then. However, configure it, and the other 2 receivers with this: DL (Destination Low address) = 0x0000FFFF and DH (Destination High Address) = 0x00.
This will put it into Broadcast mode (not unicast), and therefore will NOT require an ACK back from your receivers. This of course has some drawbacks because you won't be guaranteed with "correct" data. But it would be fun to experiment with. This way, your transmitter will send the data "blindly". But you should be able to hook one receiver up to your other stamp, and the other XBee up to the x-CTU terminal. This way you can read the data at the same time without either receiver trying to return an ACK.
Let us know what happens??
To summarize where things stand now...I have 4 XBee units, 2 standard and 2 Pro. All were used out-of-the-box without any configuration changes (until the experiments suggested in the above posts). All are being powered by either a bench power supply or a Parallax "wall wart". The two standard units communciate reliably, and the Pro unit(s) recieve reliably. The problem is when either Pro is put on the transmitter board, then comm drops out around 16 minutes after power-up. Making the suggested adjustments I end up with the same situation, all is well for about 16 minutes. Since I have 2 Pro units, I have swapped them in each experiment hoping that one would act differently, but that's not been the case. I've assembled another transmitter on a BOE and altered the program to send the same values in lieu of the temp/humidity (since there is, intentionally, no temp/humidity sensor on the BOE). The transmitter is not continuously transmitting, it sends 2 digits of temperature data, pauses 5 seconds, sends 2 digits of humidity data, pauses 10 seconds, and loops.
Of course I can't reliably know that there is not another XBee in the area, but this is a residential area and I suspect I'm the only person in range using them. Could be something else is causing interference, but why the consistent failures at the same times, and why wouldn't that affect the standard XBees as well?
I do want to switch to the Pro unit for the increased range.
I'll give bot's suggestion a try and will post results.
Thanks!
John
Is there anyway on the transmitter side you can measure the 3.3v supply on the XBee module, especially around the 16 minute time frame? Just to eliminate this as a power problem?
Or maybe I'm just demonstrating my lack of knowledge on stamps.