Hi,
I am doing a remote access experiment. There are few things I would like to clarify. I am using MC35i modem and DT80 series 3 with latest firmware.

What are the possibilities of remote access are available with this combination?

1) PPP connection from PC to DT with 2 modems at each ends.
2) email data using IP.
3) Remote access to Dex from any internet PC, using the IP address provided by the ISP.

Secondly, I need to know, using the external modem, do we have to put the AT command in the program to negotiate to get the connection established or is the command
embedded in DT firmware?

TQ [Chandran]

Good afternoon Chandran,

1/ PPP connections.
The DT80 can pick up an incoming PPP connection and create and the web services can be accessed. I have not tried dEX over a PPP connection and it might be very slow but I know you can use DeTransfer and FTP into the logger.

2/ IP.
If you have TCP/IP access then yes you can send emails. This can not work over a PPP connection and the receiving computer is unlikely to be an email server.

3/ Remote access
This is exactly what the DT8xM range is for, remote access. With a built in modem the operation is greatly simplified.
Your other option is to use a router / modem that creates a TCP/IP connection to the logger.

4/ Modem commands.
That depends on the modem and is beyond our control. We do have modem support built in to the DT80 range and it does have standard AT commands for dial up access.
If you modem needs different AT commands then yes these con be programmed into the DT8x.
BUT the DT80 is unable to open a PPP connection to a modem that would allow a TCP/IP connection to the internet.

Cheers
Roger

TQ Roger,

I am trying to connect direct cable to the host post and setup dial up connection as specified in the manual. Unfortunately, when I make a dial up, DT doesn't answer the call. I can see in the Ethernet connected Dex, the word "MODEM RX:AT" keep on repeating for about 7 times and then the connection gets cut off.

What could be the problem?

TQ [Chandran]

Hi Roger,

I've been struggling with this problem for past few days. I am not able to connect with serial port yet. I am able to connect with the USB port. What could be the problem? After I have tested with direct cable, I want to connect GSM modem at both ends and test it out. Both methods are not successful yet!

TQ [Chandran]

Good afternoon Chandran,

Have you set up the DT80 host port for a PPP connection? (Profile Host_Port Function=PPP)
You will also need to configure the PPP user name and password
Profile PPP User=(Add your user name)
Profile PPP Password= (Add your password)

Cheers,
Roger

Good afternoon Roger,

The setting are correct as you have stated. user name and password are default (DATATAKER, DATATAKER). Host port function I have tried both, ppp and command. After I set P56=16, I am able to see the word "MODEM RX:AT" keep on repeating for about 7 times and then the connection gets cut off. Looks like DT is not answering the call. Any idea?

Chandran

Good morning Chandran,

So how far in the PPP process does it get
If the Modem is sending AT then it is in command mode and is probably waiting for configuration information so please check your modem manual for the correct configuration commands.

Cheers
Roger

Hi Roger,

I am using direct cable connection (null modem). Isn't this same as setting with modem connection?

I did not connect the RI (pin9), I am not sure if this is a problem. I will try to connect the RI pin as well and test. Meanwhile, please confirm that setting for direct cable connection and modem connection are the same.

TQ [Chandran]

Good afternoon Chandran,

Yes it is a fully pinned straight through cable.

Also check that to see if your modem is set for hardware flow control and the DT80 is set to match.

Cheers,
Roger

Hi Chandran,

I will try to help solving your problem based on my experience:

1. Straight cable (RS232) is different than cross over (null) and when you want to hook into modem you need to use straight cable.

2. You only need to set the AT command into your modem once, using null cable, this can be done via data taker or hyper terminal. Check modem initialization command in your DT80 manual.

3. For straight cable and cross over you only need pin 2, 3, 7, 8 (if you make your own cable). But it is better to buy from the shop.

4. in your case, it is possible that you use null for your modem connection, null is just for configuring AT command.

5. Make sure you set the same baudrate between your datataker and modem (e.g: 19200). This may cause no connection between DT80 and modem.

6. If you prefer active and stable connection I recommend you to use GSM router such as Moxa G3111. Normal GSM modem such as MC35i has no stability for longer use (at least that what I felt when i used Siemens TC35i and MC35i).

Hope this will help.

And hello to Roger, he is an expert. In the past he taught me a lot.

Regards,
Rudy Gunawan

Good morning Chandran,

Rudy is quite correct.
Most modems will only autobaud up to 19200 so try setting the host port baud rate to 19200 and make sure Detect modem is selected in the profile
Then it should be a matter of connecting the cable and resetting the DT80 and it should detect the modem.

If you want a higher baud rate then set the comms in the modem and DT80 the same, connect the cable and reset the DT80

Cheers,
Roger

Dear Rudy,

TQ for your help. I just saw the posting today. I am successful in doing dial up connection using modem (TC35i). Unfortunately, I can collect only 3 days of data at interval of 5 minutes. If I log more, the downloading time is quite long. Related to this, I have a question. When I dial up using windows "dial up connection", it dials, then verify the username and password.

After that, I open the FTP in windows explorer and copy the file and paste it in the desktop. First message I get is "calculating the time required to copy the files". This is followed by "copying data to....". This window will be there for about 4 minutes. After the 4 minutes, the status bar suddenly change fully green and immediately close. Is this normal or do we see the status bar change gradually? Next question, is if normal to save 250kB of data in 5 minutes?

Since my connection with modem is successful, I am trying to make direct cable (cross) and want to see how it works with the same PPP settings.

TQ and best regards [Chandran]

Good morning Chandran,

It is usual to cycle the power to modems on a regular interval, usually once per day, to stop then locking up.
Also with the mobile phone network the phone is meant to be mobile. When you speck on you phone it is constantly de-registering on one cell and registering on another as you move.

If a mobile phone (Modem in our case) stays in the one place too long then it is considered by the network to be lost or stolen and disconnected from the network.
The period of time varies from from network to network and from country to country. Here is Australia it is about 4 weeks, where as in Singapore the time is 6 hours.

Once again cycling the power to the modem will cause the modem to re-register on the network and start working again.

Cheers
Roger

Hi Roger,

The modem locking up is new to me. Following your advice, I will arrange for cycling the power everyday.

BTW, I don't see the relevance to my question. With PPP connection active and I save the file with dial up connection, does it normally takes about 5 minutes to save 250kB of data?

FYI, I managed to do PPP connection with direct cable succesfully too .

Good afternoon Chandran,

Not surprise.

What is the maximum baud rate set to on the modem?
The baud rate sets the maximum transfer speed. Most modems will only auto baud up to 19200 where as the DT8xM goes to a much higher baud rates
Try setting the baud rate to 57600 or even 115200 if it can. set the host port to the same rate and turn off the auto baud function.

Even at 57600 you will be some 4 times faster.

Cheers,
Roger

Hi Roger,

The modem speed is set 115200 already. I think the bottle neck is the GSM connection, which I heard is around 9600 only! Looks like the connection between modem and DT is fast, but modem to modem is slow!

TQ [Chandran]

Hi Chandran,

Some comments to your previous post:

1. Even though GSM modem can go 115 k baudrate, most of network provider only give support up to 19.2 k (in my home country, as this is considered as dial up).

2. If you use dial up, then it is normal to have waiting period for 3 days data of 5 minutes interval. Connection speed is slow, it is not recommended to use this conn for huge number of data.
   Solution: you should retrieve the data everyday

3. Other solution for no 2 is to let data taker send the data (via GSM modem) to your PC periodically.

4. Modem lock up depend on the network, in my country it is in 2 - 4 weeks depending on operators. This is happen as network system tries to shut down inactive link (transmission of small amount of data over several days period can be considered as inactive) for efficiency purpose, while the modem can't detect this.

Solution: You can put digital switch of DT to your modem power.

Regards,
Rudy Gunawan

Thanks for your comment Rudy. I am interested in item #3. Could you clarify how the DT send data to PC daily? What is the setup in PC for the DT to dial in to PC?

TQ [Chandran]

Hi Chandran,

There are four methods of sending data to your PC, three are a bit complex and the last maybe is the easiest:

1. Use SMS
   You can put at+cmgs command in data taker, however you need to prepare SMS gateway and small program (software) to translate SMS into the required data format at your PC. I used this method before, the downside is only SMS delay specially when holiday season

2. Use direct dial up connection
   Dial up your PC from data taker and you can monitor the data through hyperterminal. Again you will need separate program (software) to capture the incoming data and translate them into the required format. I used this method before and I didn't quite happy with the result.

3. Use GSM router
   You can establish TCP/ IP communication using this router. Your router is self registering with network providing with public IP, while the connection between data taker and the router can be created using local IP address.
   For the other end you need to estabish FTP server to capture the data (data will be in text file). You can easily set the data duration which you want to send.
   I also used this method for creating a vast network contain of more than 100 data taker, quite fast and good delay mostly because clogged up at the server.

4. Using DT8xM
   Using integrated data taker modem, you just need to follow manual instruction. I haven't try this new stuff. better ask Roger for help.

Regards,
Rudy Gunawan

Hi Guys,

It all depends on exactly what your application requires.
As you would expect my preferred option would be to use a DT8xM. It has the advantage of being an integrated solution and so is easier to configure in teh first place.

The dial in option can be considered and the DT80 supports modems. The down side is the transfer speeds. The data rates are much slower than a network enabled solution.
You also need to consider the phone network at your office too. Most offices now days have either a digital PABX or VoIP both do not support an analog modems so you will need a dedicated analog phone line to access the logger, but even then you will not be able to access the network interface.

The option of a GSM/2G/3G/4G router / modem is a good solution for a DFT80 as it will give you a network connection.
The better router / modems will allow you to configure VPN's etc. but they do cost more.

Cheers,
Roger