Technical Note # 640 VT-MODEM Interfaces with a PLCDirect DL250 PLC Abstract: This Technical Note is based on documentation provided by Automation Direct. It defines the procedure for dialing and establishing communications between a PC running Directsoft32 software and a DL250 PLC via SIXNET Industrial modems. The Automation Direct DL250 can be remotely controlled via analog phone lines and SIXNET VT-MODEMs. Although a DL250 is concentrated on in this document, the D0-05, D2-250, D2- DCM, D3-350, D3-DCM, D4-450 and D4-DCM PLCs will work as well. Software Used: Directsoft32 VT-MODEM Setup Wizard v1.15 Hardware Used: (1) Automation Direct DL250 PLC (1) D2-DSCBL-1 adapter cable (1) Null modem cable (1) SIXNET VT-MODEM-1 Industrial Modem (1) SIXNET VT-MODEM-2 Self-Dialing Modem (2) VT-CABLE-MDM (Male to Female DB9 straight thru serial cable) Alternative PLC Note: When using one of the other valid PLCs mentioned in this technical note, a different cable may be required. Each PLC will need the cable as defined below in conjunction with a null modem adapter cable. PLC Cable D0-05 Port 2 D2-DSCBL D2-250 Port 2 D2-DSCBL-1 D2-DCM D3-DSCBL-2 D3-350 Port 2 D3-DSCBL-2 D3-DCM D3-DSCBL-2 D4-450 Port 1 D3-DSCBL-2 D4-450 Port 2 D2-DSCBL D4-DCM D3-DSCBL-2 TN640.DOC PAGE 1
D2-DSCBL-1 for D2-350 and D3-350 DB15 Male to DB9 Male to DL250 PLC Port 2 VT-MODEM VT-CABLE-MDM DB9 Female to PC DB9 Male to Modem DCD 1 1 DCD TXD 2 3 TD RD 2 2 RD RXD 3 2 RD TD 3 3 TD DTR 4 4 DTR GND 7 5 GND GND 5 5 GND DSR 6 6 DSR Tie pins 4 and 5 together Tie pins 7 and 8 RTS 7 7 RTS together CTS 8 8 CTS RI 9 9 RI D2-DSCBL for D2-05 and D4-450 D3-DSCBL-2 for D2/D3/D4-DCM and D4-450 RJ-12 Female to Port 2 DB9 Male to VT-MODEM DB25 Female to Bottom Port of D2-350 DB9 Male to VT-MODEM TXD 4 3 TD TXD 2 3 TD RXD 3 2 RD RXD 3 2 RD GND 1 5 GND GND 7 5 GND Tie pins 7 and 8 together Tie pins 4 and 5 together Tie pins 7 and 8 together Installing the SIXNET Industrial Modem Driver to Windows PC: To configure Windows to recognize the VT-MODEM, go to Start Settings Control Panel Phone and Modem options. Next, go to the Modems tab in the Phone and Modem options window, and then click on Add Next, check the Don t detect my modem; I will select it from list box and manually select Standard 28800 bps Modem from the modem type list. Refer to screen shots 1, 2, and 3 for details of how the modems were configured. This will configure the modem driver so Directsoft32 can use the Windows TAPI control when accessing the modem. TN640.DOC PAGE 2
Screen Shot 1 Screen Shot 2 Screen Shot 3 TN640.DOC PAGE 3
Configuring the Industrial Modems: VT-MODEM-1 - Connect the VT-MODEM-1 to the PCs serial COM port via the VT-CABLE-MDM (Straight-thru serial cable). Open the VT-MODEM Setup Wizard provided on the latest SIXNET CD or SIXNET website (www.sixnetio.com). Click the Open Configuration File button to use the preconfigured Direct_Logic_PLC.6ms file provided on the SIXNET CD or website. Click the Next button and choose the VT-MODEM-1 (See Screen Shot 4). Click on the Next button. Enter the COM port number the VT-MODEM-1 is connected to on your computer (COM Port 1 in this case. See Screen Shot 5). Click on the Next button two more times to enter the Write Configuration Window of the VT- MODEM Setup Wizard. Click on the Write Configuration to Modem button to write the configuration to the VT-MODEM-1 s memory (See Screen Shot 6). To configure the Wizard manually, refer to the screen shots below. Screen Shot 4 TN640.DOC PAGE 4
Screen Shot 5 TN640.DOC PAGE 5
Screen Shot 6 VT-MODEM-2 A VT-MODEM-2 is used in this step, but it can be replaced by a VT-MODEM-1 so long as the Self-Dialing feature is not needed. Configure the VT-MODEM-2 in the same manner as the VT-MODEM-1. After opening the Direct_Logic_PLC.6ms modem wizard configuration file, select the VT-MODEM-2 (PLC Self-Dialing Modem) in the Read Configuration window. To enable the Self-Dialing feature in the VT-MODEM-2, go to the Self-Dial Parameters window and select the Enable Self-Dial check box. Enter the phone number the VT-MODEM-2 is to dial in the First Phone # field. In this example, phone number 5554444 was used (See Screen Shot 7). The selections of other features in this field are optional. Go to the last window of the VT-MODEM Setup Wizard and write the configuration to the modem. TN640.DOC PAGE 6
Screen Shot 7 PLC Port Setup: This setup shows a 250 bottom port setup. Other PLC setups will differ slightly but follow the same parameters appropriately. Note: the DCM modules are not configured through Directsoft. You must configure the dipswitches and selector switches for the proper setup on these modules. Again, follow the same parameters guidelines from this example and refer to the DCM manuals for the appropriate settings. You must first connect to the programming port of the PLC. On the 250, this is the top port (RJ12 connector). Consult the Directsoft programming manual to establish a link to the PLC. In the Main window of the Direcsoft32 Programming Software, go to PLC Setup Set Sec. Comm. Port (See Screen Shot 8). Set the port up as indicated in Screen Shot 9, then send the settings to the PLC by clicking on the indicated button. TN640.DOC PAGE 7
Screen Shot 8 TN640.DOC PAGE 8
Screen Shot 9 DirectSoft32 setup: The following steps show how to setup a modem connection through the programming software to diagnose and make changes to an AutomationDirect PLC via a phone line. On the PLC side, you connect your cables up as shown at the beginning of this document. You will need to connect your modem to a phone line and establish the number, extensions and delays that are needed for your connection. You will also need to determine whether a 9 is needed to dial out of your local side. First, create a link and choose Modem from the Ports list. Consult the Directsoft32 programming manual to find the steps to creating a link (See Screen Shot 10). Choose the PLC CPU that you are connecting to (See Screen Shot 11). Click on the port tab, choose the modem driver that you created earlier on your PC and enter in the phone number to the PLC that you are trying to connect to. You will need to add a 9 if this is required in your facility. You may need to add commas for time delays when appropriate. One comma equals two seconds (See Screen Shot 12). Click on the Protocol tab and choose the K-sequence protocol and setup the time delays as shown in Screen Shot 13. Choose Accept when complete and click Yes to check the connection. DirectSoft32 will initiate the local modem and dial up the remote modem and attempt to connect to the remote PLC. If everything works correctly, then you will see no additional windows and you will see your link in DSLaunch, showing a good status. If there is a problem, the error window in Screen Shot 14 will appear defining the problem. TN640.DOC PAGE 9
Screen Shot 10 Screen Shot 11 TN640.DOC PAGE 10
Screen Shot 12 Screen Shot 13 TN640.DOC PAGE 11
Screen Shot 14 Conclusion: This test successfully established communications between a PC and PLC Direct PLC via SIXNET industrial modems. Troubleshooting: 1. Remote modem is not answering: - Isolate the problem to either the remote or local side. Try dialing the remote modem with a telephone. If the remote modem rings (indicated by a short blip on the RD LED), answers and attempts to negotiate a connection, then there is probably something wrong with the local modem setup. If the remote modem doesn t ring, connect or answer, you may have a problem with the remote setup. - Make sure that the remote modem configuration has auto answer turned on. You also need to have a number of rings selected. - Try removing the cable between the remote modem and PLC. If it answers then, you know the problem is in the remote cable connection. Consult the diagrams towards the beginning of this document for the correct pinout. If possible, try using the programming cables provided by Automation Direct as well as the null modem adapter that comes with the modem. - Try a different cable on the local modem. - Verify settings for modem driver on the PC. Consult the appropriate section of this document on how to set this driver up in windows. 2. Remote modem answers but the PLC doesn t connect: - If at all possible, try to connect to the PLC directly from the serial port of a PC. Verify that the PLC port is Ok. - Phone line problem. Use another phone line if possible. - The PLC port has not been configured or is configured improperly. Consult the section in this document that describes the port configuration. - Verify the remote modem configuration. Follow the steps in this document again and re-download the configuration to verify the setup. - The modem driver is not configured properly. Consult the steps in this document to verify modem driver setup. - The wrong modem may be answering. This can happen on a phone network in some facilities. Have someone power off the remote modem and attempt to connect again. If something answers, there is a problem with the phone network that needs to be corrected. - The remote modem is not on a dedicated line. PBX (Private Branch Exchange) lines will cause problems with many different software packages. TN640.DOC PAGE 12
3. The PLC connects but I lose connection intermittently whether program status is turned on or during a program transfer. - Poor phone line quality. Sometimes there is no way to resolve this. Be sure that the phone line on the remote end is not run around devices that cause high RF signals, such as frequency drives. You can often tell the quality of a phone line by actually calling someone and talking on this line. If it is very noisy, then it is most likely that you will have problems using it for PLC connectivity. - Poor cable quality between PLC and modem or PC and modem if using an external modem. If the cable between the modem and PLC is routed around devices that generate high RF signals, you will most likely have problems with your connection. They will need to be isolated. Distance between the PLC and the modem could also be a factor. 50 ft. is the maximum length for RS232. You may achieve this distance depending upon your environment (high RF signal devices). - Raise the timeout and retries in the link editor in Directsoft32: If you are still experiencing problems after following these steps, contact AutomationDirect s tech support at (770)844-4200 or SIXNET s Tech support at (518) 877-5173. TN640.DOC PAGE 13