Although Sixnet VT-Modems are relatively easy to use, there can be instances where more complex situations can arise when connecting them to other devices. Since the VT-Modem-4 must be used in pairs, it is necessary to configure one unit as a “Master” and the other unit as a “Slave” (It doesn’t matter which unit you configure to be the master modem or the slave modem). You must use the Sixnet VT-Modem Wizard to configure your modems. Please see the sections below:
- Introduction to the VT-Modem-4
- Troubleshooting and Frequently Asked Questions
- Using the VT-Modem Wizard to configure your Modem
- Technical Notes for connecting to various PLC’s and other equipment
Introduction to the VT-Modem-4
The following information is contained in the VT-Modem-4 User Manual, in addition to the information found in this document. It can be downloaded from:here
The following sections are contained in the user manual:
| Section 1 | Overview |
| Section 2 | Performance Specifications |
| Section 3 | VT-Modem Mounting |
| Section 4 | Electrical Connections |
| Section 5 | Modem Configuration |
| Section 6 | Leased Line Connections |
| Section 7 | Maintenance Information |
| Section 8 | Product Support |
Troubleshooting and Frequently Asked Questions
1. I can’t seem to detect the VT-Modem-4, why?
Answer: Verify the following:
- Verify that you have selected the appropriate com port that is connected from your PC to the VT-Modem-4.
- Verify that you are using a DB-9 Null-Modem cable.
- Verify that you have applied 10-30 VDC to VT-Modem-4.
2. I ordered a VT-Modem-4, but it is being detected as a VT-Modem-1, why?
Answer: Make sure that you are using the latest version of the Modem Wizard (V2.11 29DEC09). If you are on the latest version of the Modem Wizard and still detecting a VT-Modem-1, then this is usually caused by the Modem Wizard Software detecting your PC’s internal modem. Follow the steps in 3a-e below to determine if this is the case.
3. I can’t write my configuration to the VT-Modem-4. I keep getting an error message that says problems encountered while sending string AT…..etc. See error example below:
Answer: This is usually caused from the VT-Modem Wizard Software detecting the internal modem of the PC and not the internal socket modem of the VT-Modem-4. Follow the steps below to determine which modem you are actually detecting:
a. Open up a terminal emulator program, such as, hyperterminal, teraterm, or the Run Terminal Emulator Icon in the VT-Modem Wizard Software.
b. Type the command ATI3 and hit the enter key on your keyboard. You should see one of the following; LT V.92 1.0 MT5634SMI-V92 Data/Fax Modem Version 1.28d or Agere OCM V.92 MT9234SMI Data/Fax Modem Version 1.02k. If you see any other alphanumeric characters not described above, then you are detecting the internal modem of your PC and not the VT-Modem-4.
c. If you see nothing after typing the ATI3 command, then type the command ATE1 and hit the enter key on your keyboard and repeat the ATI3 command. If you still see nothing, you may still be detecting the internal modem on your PC.
d. If you do see the alphanumeric characters described above but still can’t write the configuration to the VT-Modem-4,report error message to support here: https://redlioncontrols.zendesk.com/hc/en-us/requests/new
e. To force the Modem Wizard Software to detect the VT-Modem-4 and not the internal PC Modem, see #4 below:
4. How do I get the VT-Modem Software to detect the VT-Modem-4 and not my PC’s internal modem?
Answer: Follow the steps below to disable you PC’s internal modem:
a. Click on Start, My computer, and then View System Information under the System Tasks. You should see the System Properties below:
b. Click on Hardware tab and you should see:
c. Click on Device Manager and you should see a Modems section:
d. Click on the + sign, then right click on your PC’s internal modem and select Disable :
e. Select Yes and you should now see a red x on your selection indicating that it is now disabled:
f. Restart your computer and you should now be able to detect the VT-Modem-4 using the Modem Wizard Software.
5. Can I use a 4-wire leased line or a digital leased line to connect the VT-Modem-4’s? What is the difference?
Answer: The definition of leased line has changed and is somewhat generic. Please see the descriptions below:
a. It used to be two phone lines logically connected through the telephone network. This basically means they take a normal voice line, take the dial-tone off and connect them together. Instead of picking up the phone and dialing, two people could pick up the phone and just start talking to each other (kind of like the old can and a string trick). This voice line is always connected and is only point-to-point. When modems are used in this situation they use the same modulation protocol that a dial-up modem would use when calling an ISP or another modem. There is no distance limitation on this application.
b. Leased line has also been referred to as a cable run (buried in the ground) by the customer. This type of application could be twisted pair cable, and is usually meant to be used by a line driver modem. These modems usually have very specific distance limitations and use proprietary protocols. An example of this product is http://www.blackbox.com/Store/Detail.aspx/19-2-kbps-RS-232-Line-Drivers-Standalone/ME760A-R2.
c. Leased line is commonly known as an always on internet connection by the phone company. A good example of this is a T1 or T3 line.
The SIXNET modems were designed for use in application (a) above. In this type of application, the modem must be on a 2-Wire Voice Grade line. The modem is not compatible with 4-wire lines. 4-wire is not just an additional pair added to the 2-wire application. The wiring is different. We have had a customer successfully use the VT-MODEM-4s in an application where the customer ran a cable for 3km. In this application the user has to carefully watch the signal loss from one end of the line to the other. Acceptable signal loss is described on page 13 of the user manual.
6. I can never get a carrier detect (CD) LED, unless I remove the devices that are connected to the serial port. How do I fix this?
Answer: Sometimes PLC’s or other serial devices send random characters that may interfere with the connection. To fix this, Go to the Leased Line Configuration page of the VT-Modem Wizard and select Block Com Port Till Connected.
7. If I cycle power or lose power to one VT-Modem-4 while connected, I can’t seem to re-establish a connection.
Answer: It is possible for the remote VT-Modem-4 unit to get stuck in a carrier detect (CD) LED “On” state. If this is the case, you will have to cycle power to the unit. To prevent having to drive to the remote location or having someone cycle power for you every time that this situation occurs, enter the following command in the user defined “AT” String on the modem parameters page of the wizard, or terminal emulator in the wizard, or through another terminal emulator program. ATS10=8S30=3
8. I can’t detect the modem when I click on the “Red Bar” to detect the modem.
Answer: Make sure that you have the most current version of the Modem Setup Wizard, currently V2.11 29DEC09. Verify that your PC and Modem have power applied to them. Verify that you are using a DB-9 Null Modem cable. Verify that you have selected the correct serial com port. It may be required for you to cycle power on the VT-Modem-4 that isn’t responding and click on detect the modem within 5 seconds of applying power back to the unit.
Follow these steps:
Remove power, then apply power, count to 3, then click on detect modem in the modem wizard.
You should see a box to select Leased line modem or 56k modem, select leased line modem. It should then detect the modem.
9. Does the Master or the Slave initiate the call?
Answer: They are directly connected devices via a virtual circuit (leased line) that the phone company provides or a dry run directly connecting the devices together with a 2-wire RJ-11 cable.
Using the VT-Modem Wizard to Configure your Modem
Download Instructions and Procedures
1. To download the latest version of the Sixnet VT-Modem Wizard, go to http://www.redlion.net/files/1319/7177
After downloading, follow the installation instructions to install the wizard.
2. Open the VT-Modem Wizard Utility
3. Click Next :
4. Connect a DB-9 cable from your PC to the VT-Modem-4, select the appropriate device COM port and apply power.
5. Click on the Red Bar at the top that says “NO MODEM DETECTED. PLEASE CLICK
HERE TO DETECT THE MODEM”. You should see:
6. Click on Leased Line Modem and you will see a blue bar with VT-MODEM-4 (Leased Line Industrial Modem), Rev 1. (Note – It may say Rev 2, depending on internal socket modem). If it detects the modem as a VT-Modem-1, see Section 4 for troubleshooting.
7. Set the communication parameters for the serial device that you will be connecting to and click Next to see the Leased Line Configuration Page:
8. To configure the “Master” Modem, Click on the radio button for “Leased Line Master” and it should illuminate light blue as it appears above and click Next to see the Modem Parameters Page:
9. Select the appropriate Modem to Modem Parameters. We recommend the default settings except for an Auto detect Speed of 33600, unless specified differently in a .6ms configuration or by a 3rd party device specification.
10. Click Next, and click on Write Configuration to the Modem:
11. When the modem has been successfully loaded, you should see:
12. To configure the Slave Modem, follow steps 2 through 11 above. The only difference is for step 8, you would click on the radio button for Leased Line Slave.
13. We recommend that you save your Master and Slave configuration files in case it becomes necessary to configure a similar project, or in the event that the modem has to be replaced.
Disclaimer
It is the customer's responsibility to review the advice provided herein and its applicability to the system. Red Lion makes no representation about specific knowledge of the customer's system or the specific performance of the system. Red Lion is not responsible for any damage to equipment or connected systems. The use of this document is at your own risk. Red Lion standard product warranty applies.
Red Lion Technical Support
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