Network Operation and Troubleshooting
Contents
1. 7 5 Network Operation and Troubleshooting PWR or OK off PLC power is disconnected DCM is defective Check the PLC source power Replace the DCM MSTR off and DCM is in a master station Switch setting is incorrect Remove power from the PLC remove the DCM and check switch positions1 and 2 on SW5 ENQ indicator does not come on when communications program is executed The PLC master station is not in Run mode Online Offline switch is in the Offline position Communications program is not correct Place the PLC in Run mode Set the switch to Online Check the communications program Verify the address amount of data and data type are correct ENQ stays on but NAK TOUT or HDR indicators do not come on at all Communication timeout is disabled RTS and CTS signals are not looped back on the master station end of the cable Remove power from the PLC remove the DCM and check switch position 3 on SW5 Remove master station connector ensure that RTS and CTS are connected according to the cable diagram ENQ comes on and TOUT indicator flashes RLL communications program is not correct Modes are different Communication cable Check the communications program Verify the address is correct Set baud rate parity and mode HEX ASCII to match the master station Verify the cable is wired according to the cable pinouts ENQ indicator comes on and NAK indicator flash2. Network Operation and Troubleshooting In This Chapter Starting the network Troubleshooting 7 2 Network Operation and Troubleshooting Starting the Network PLC as Master If you re using a PLC as the master station you must put the CPU in Run mode Networks before the communications program can be executed This is because the PLC master uses RLL instructions included in your application program to initiate the data transfer requests There are two ways to place the CPUs in run mode e Turn the keyswitch to the RUN position e Turn the keyswitch to the TERM position and use a programming device to change the operating mode documentation that came with it for network startup information If you created your own DirectNET program you ll have to execute the program file to get things started Check the documentation for your particular programming language to determine the steps required to execute program files Slave Stations Depending on your application you may also have to place the slave PLCs in Run mode to obtain meaningful data The DCM and DCU interfaces also have On line switches that must be in the On line position before communications can begin CPUs with built in ports do not necessarily have to be in Run mode but again the data may not be current S2 PLC Peer as PLC Peer master networks require both CPUs be in Run mode since either station vo Master Networks can initiate data transfer requests Both stati
3. atchdog timer has expired O power is on If an external power supply is used both base power and the external supply must be on 1 7 Network Operation and Troubleshooting The following table provides additional troubleshooting details for the DL305 DCU PWR off PLC power is disconnected Check the PLC source power DCU is not connected to the CPU Make sure the DCU is securely fastened properly to the CPU and that no connector pins are bent DCU external power source if used is Check the external power source not connected DCU is defective Replace the DCU DIAG off DCU is defective Replace the DCU DATA does not flash during Loose or incorrectly wired cable Check the cable connections and pinouts a Z communications Online Offline switch is in the Offline Set the switch to Online SZ position Communications program is not correct Check the master communications re k ep program Verify the address amount of 5 E data and data type are correct See 2 a Appendices D E and F for address references Be
4. es slave responds but the data is incorrect Modes are different Communication cable Set baud rate parity and mode HEX ASCIl to match the master station Make sure the and connections are correct RS422 Check pin 7 GND if you re using RS232C ENQ and HDR indicators come on and the NAK indicator flashes Communications program is not correct Modes are different Check the amount of data being transferred You must use the correct byte boundaries for the data type being used Set baud rate parity and mode HEX ASCIl to match the master station DATA indicator is on but the NAK indicator comes on intermittently Electrical noise Make sure the system has good earth grounds Only one end of the cable shield should be grounded If you re using RS232C try using RS422 Bunooysejqnol 8 Z iq oO 3 O g9 ped oO 5 7 6 Network Operation and Troubleshooting DL305 DCU Indicators Check the DCU indicators to verify the DCU is operating correctly The following diagram shows the proper indicator conditions On when PLC is in On when data is Run Mode oe being transmitted RUN vata QO d Cc 2 w D Q x p fe zZ amp Troubleshooting On when PLC BATT Dae O On when internal battery needs oes diagnostic tests are replacing ia O pwr O ae complete On when CPU On when base w
5. ons contain the necessary RLL 2 e instructions N i Host as Master Host master networks require a DirectNET communications program to manage Networks the data requests If you re using a host software package you should check the ZS 7 3 Network Operation and Troubleshooting Troubleshooting First Place to Look Try an Example Program CPUs with Built in DirectNET Ports Host Masters Communication Interface Indicators If the network does not seem to be working correctly check the following items 1 Cable and connections Incorrectly wired cables and loose connectors cause the majority of problems Verify you ve selected the proper cable configuration and check to see the cable is wired correctly 2 Switch settings Make sure you ve set the slave stations to match the communication parameters required by the master station DCM operator interface or host computer 3 Incorrect protocol Make sure your network stations are all set for the same protocol DirectNET networks can use the DirectNET or HostLink CCM2 protocol selections 4 Communications program Check the communications program for errors Sometimes it is helpful to have an example you can try AppendicesA B andC provide examples of the three network configurations You can quickly and easily build a small network to make sure you are following all the appropriate steps These are especially helpful if this is your first DirectNET ap
6. plication Most problems that occur with the CPUs are related to communication settings Check the switch settings and or use a programming device to check the station address DirectNET programs must manage all aspects of network communication including timing considerations Chapter 6 provides information on network timing issues that can affect network performance The communications interfaces DCMs and DCUs have indicators that are specifically for communication status The following paragraphs show these indicators and describe their meanings Bunooysejqnol 8 Z D _ fe mi A no D o fe 5 7 4 Network Operation and Troubleshooting DL405 DCM Check the DCM indicators to verify the DCM is operating correctly The following Indicators diagram shows the proper indicator conditions Module Power Dae Self Test Indicator ON ON ia Send Receive Enquiry NAK ON ifa pwn Mm mo FLASHING NAK is either Nak m ENG __ Send Recsive Header sent or ON eee a FLASHING TOUT ON if a Send Receive Data timeout has Packet FLASHING occurred in the DCM Master Mode 52 ON if master 2S OFF if slave o 22 Q 28 x oO o gt gt IE Z D o gt oo o 5 o o o o o 5 oo o o o The following table provides additional troubleshooting details for the DL405 DCM
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