APPNOTE: Setting up a Power Master Logger to operate over a modem

Article ID: 060314sab
Last Reviewed: July 7, 2023

The information in this article applies to:

  • Power Master Data Loggers when using a modem link to communicate with Pronto for Windows 5.00 or later.

Target Audience

This article is aimed at:

  • All Users of Power Master Loggers with modem links.


The Power master series of Loggers can be configured to allow Pronto for Windows to connect, control and download them over a Modem link.
This application note details the steps required to setup and test a modem link.

See details of our Power Quality Monitoring Equipment.

Before You Start

In order to setup and test a Modem link, you will require the following items:

    1. A pair of modems. At least one will need to be a stand alone external modem with either a 25 way or 9 way female connector.
    2. A computer with a spare serial port. If using two external modems you will need two spare serial ports. If you do not have a computer with two serial ports, you may use two computers with a port each. A USB to Serial converter can be used with those computers that have no available serial port. Please refer to APPNOTE:Using a USB to serial converter with a Ranger Logger for more information.
  • Two phone lines, one for outgoing and one for incoming calls.
  • A PM3000 modem adapter. You may make this yourself if you wish, as it is very simple, the connection diagram is below. Alternatively contact your dealer.
  • One of the following Loggers:
    PM6000 (standard) with firmware Rev 0.130 or later.
    PM6000 (standard with revised PSU) Rev 1.138 or later.
    PM6000 (waveform capture) with Rev 2.004 or later.
    PM3000 (low speed) with firmware Rev 1.014 or later.
    PM3000 (high speed) with firmware Rev 1.054 or later.
    PM3000 HF with firmware Rev 2.004 or later.
  • The text terminal utility program TermView.exe.
    This utility is installed with Pronto for Windows versions 5.37 or later.
    This utility is present in the Tools subdirectory on the CDROM in versions 5.30 to 5.36.
    You may use another text terminal utility such as Hyper-Terminal if you wish, however the instructions below refer to TermView.exe.

Step 1: Test the settings for the local modem.

The local modem is the one used by your computer to dial out to the Logger.

You can test which settings to use by opening TermView.exe, selecting the modems COM port from the PORT menu and typing them in directly.The minimum required is the following:

Type AT<return>    to which the modem should respond: OK

Type ATZ <return>  to which the modem should respond: OK

Type ATDT0123456789<return> (replacing 0123456789 with the phone number of your other line), whereupon the modem should call the specified number.

I suggest you start off calling a voice line you can answer when it rings and you should hear the modem trying to establish a connection.

Step 2: Enter the local modem settings into Pronto for Windows.

This is done from within Pronto by clicking on the TOOLS-OPTIONS menu and then choosing the tab labelled MODEM.
When testing this with an internal PCI modem, I selected the modem type “Generic External” and the only setting to change was the “Configuration string from “AT&F0&C1&D2” to just “ATZ“.
You can now test this by creating a new Logger Address with the appropriate COM port and phone number specified, then selecting  PLAYBACK or CONTROL PANEL from the LOGGER menu. Pronto should then dial the number you specify and time out after 60 seconds.

Step 3: Test the settings for the remote modem.

The remote modem is the one connected to your Logger that receives the call from your computers local modem.

You will need to work out how to get your modem to perform each of the following functions:

  1. Set the modem to answer incoming calls automatically.
    This is known as “Auto Answer”. In the modems I have tested this can be done using TermView.exe and sending the commands:
    Type AT<return> to which the modem should respond OK.
    Type ATS0=2<return> to which the modem responds OK. This sets the modem to answer after 2 rings.
    Some modems have different settings to turn on auto answer, or you may find some small switches that control the auto answer mode.
  2. Set the modem to start at 115200 baud when power is applied.
    Since the modem will have power removed and re-applied when it gets to a remote location it is important that the baud rate it starts up at matches that set in the Logger.
    In the modems I have used this is normally a case of getting the modems attention using the AT command at the rate you wish to use and then writing the current modem settings into its non-volatile memory.  To save the modem settings use a command such as AT&W0. This command does vary between modems so you will need to read the modem manual here.
  3. Test the remote modem settings.
    Connect the local modem to one or your serial ports and the remote modem to another.
    Connect the local modem to the outgoing phone line and the remote one to an incoming phone line.
    Power the remote modem off and then on again (this ensures it is now at the same baud rate it would be at after transport to where it is intended to be used).
    Open two windows in TermView.exe (or two copies of TermView).
    Open both ports in TermView but do not send anything to the remote modem.
    Send the AT command to the local modem, then the ATDT0123456789 command (replacing 0123456789 with the number of your incoming phone line).
    The remote modem should output the word RING a couple of times and then answer the call.
    Once negotiation between the modems is complete, you should see a line starting with the word CONNECT and then giving the connection details appear at both ends.
    This test is now complete, you may power off either modem to break the connection.

Step 4: Test the two modems with Pronto for Windows.

Using the modems as connected in step 3 but with a single copy of TermView.exe running connected to the COM port for the remote modem.
In Pronto for Windows select the item CONTROL PANEL from the LOGGER menu, and then select the Logger address created in step 2 above.
You should see the following occur:

  1. Pronto for Windows dials out from the local modem.
  2. As in step 3 the word RING should appear a couple of times.
  3. The remote modem will answer the call and the line containing CONNECT should appear.
  4. This will be followed by two lines containing this text: “:0055011400000000000000000000FFFFFFFFFFFF00F7591339
  5. Pronto for Windows will display this message: “The Logger is not responding.” and then hang up the phone line.

Step 5: Test the two modems with Pronto for Windows and the Logger.

Using the modems as connected in step 4 but with the remote modem connected through the modem adaptor to the Logger.
Again select the item CONTROL PANEL from the LOGGER menu, and then select the Logger address used in step 4.
You should see the same process in steps 1 and 4 above (but you will not be able to see the remote modem output unless you have an RS232 monitor lead as shown below:
The logger should wake up (if it is asleep) and Pronto for windows will connect to it and put up the Control Panel dialog allowing you in interact with it.

Building a modem adaptor

In the past we have built the adapter into one of the plastic cases available here:
or here:

If building a 9 way to 9 way adaptor the connections are as follows:

Signal name 9 way male (Logger) 9 way male (modem)

modem data to Logger

pin 3 pin 2

Logger data to modem

pin 2 pin 3


pin 5 pin 5


no connection link pins 6 to 4


no connection link pins 8 to 7

If building a 9 way to 25 way adaptor the connections are as follows:

Signal name 9 way male (Logger) 25 way male (modem)

modem data to Logger

pin 3 pin 3

Logger data to modem

pin 2 pin 2


pin 5 pin 7


no connection link pins 6 to 20


no connection link pins 5 to 4

If building a 25 way to 25 way adaptor the connections are as follows:

Signal name 25 way male (Logger) 25 way male (modem)

Modem data to Logger

pin 2 pin 3

Logger data to Modem

pin 3 pin 2


pin 7 pin 7


no connection link pins 6 to 20


no connection link pins 5 to 4

Building an RS232 monitor lead

One useful thing I have used in the past is a RS232 monitor cable that consists of a pair of back to back 9 way male and female connectors and then another pair of 9 pin female connectors that allow monitoring of the TX and RX data flowing between any two connectors:

    9 pin male                  9 pin female            9 pin female     9 pin female

    from PC / Logger             to modem               monitor 1        monitor 2    pin 1 ———————- pin 1
pin 2 ———————- pin 2 —————- pin 2
pin 3 ———————- pin 3 ——————————— pin 2
pin 4 ———————- pin 4

    pin 5 ———————- pin 5 —————–pin 5 ———- pin 5
pin 6 ———————- pin 6

    pin 7 ———————- pin 7
pin 8 ———————- pin 8
pin 9 ———————- pin 9

To monitor the data flowing in both directions you will need two additional serial ports, one connected to monitor 1. and the other to monitor 2. Alternatively if only a single port is available just monitor the data in one direction at a time using TermView.exe