RS-422/485 MDrive products can appear to have a communications failure when it is merely in a mode that prevents it from responding to or echoing back, instructions in SEM Terminal.

Settings that can cause this include

  • Party Mode (PY=1)
  • Checksum (CK=1)
  • Echo Mode (EM=1or2)
  • Incorrect Baud Rate (BD)

Also, check the scroll bar in the terminal window. If it is not all the way down, you may not see what the driver sends back.

When you have communications problems, the simplest fix may be to set your driver back to factory defaults using the instruction “FD”. To prevent defaulting all the drivers in your system, you may want to plug your communications cable into only the driver you are working on.

Make sure that you have a backup copy of the all variable settings and program before doing this.

By inserting a string of text into one of the function keys in a Terminal window in SEMTerminal, it can be sent to the driver as a continuous string of characters:

(copy / paste string above) To do this, open SEM Terminal and click on the terminal window. If there is no terminal window open, open one using View > New Terminal Window.

Figure 1: Terminal window showing function key group

Right-click on the function key area at the bottom of the terminal window. The function key setup dialog will open.

Figure 2: Function key setup dialog
Pick one of the function keys and type something like “Reset FD” into the Caption. Then highlight, cut and paste the character string given above into the Contents window of that row and click on Done. When that function key is pressed, the string will be sent. Note that there are delays in this string and it takes about 4 seconds to complete. When you are able to communicate with the driver, type “S” then a carriage return. This will save the defaults.

If you still haven’t established communications, try setting SEM Terminal to different baud rates. This is done by Right-clicking the text area of the terminal window and select Preferences.

Figure 3: Terminal settings dialog
Figure 3: Terminal settings dialog

 

Then select the Comm Settings tab. Select the baud rate desired and make sure that the radio button for MDrive is selected. Select Done, then try your function key. You may have to try all the possible baud rates.

Check Hardware and wiring

Check power supply and cabling
  • Check cabling and connections from:
    1. AC Line to DC motor voltage supply.
    2. DC supply to Lexium MDrive.
  • When power is ON, LED 1 on the upper-right of the Lexium MDrive heat sink should be solid green.
Check Communications adapter and cabling – SEM MD-CC404/5-000
  • Ensure the adapter is firmly seated in the USB port of your PC or notebook
  • Verify that the DB9 is firmly seated and the screws are tightened. If M12, verify the connector is fully inserted, and the bayonet-lock is engaged.
Check Communications adapter and cabling – Third-party adapter/cable
  • Ensure the adapter is firmly seated in your PC or notebook
  • Verify that the DB9 is firmly seated and the screws are tightened. If M12, verify the connector is fully inserted, and the bayonet-lock is engaged.
  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx).
  • Using a multimeter, ring out the cable conductors to verify correct connection of all signals

Check software settings

Verify selected COM Port settings
  1. Open both the Motion Control Programmer settings dialog and the Computer’s Device Manager. Verify that the selected COM port matches what the adapter is installed on.
  2. In the device manager, right-click on the COM port, select “Properties.”
  3. Verify that the adapter drivers are operating correctly as indicated in the “Device status” text area (1). Do not close the properties dialog.
  4. Click the “Port Settings” tab of the COM Port properties dialog, verify the selected BAUD rate matches that set in the Motion Control Programmer Terminal settings dialog.
Verify Lexium MDrive settings
  1. On the Motion Control Programmer, select the menu View > Find Comm. Settings, Click Find (1).
  2. Wait while the test runs through the various BAUD Rates/Settings. If settings differ from the defaults, adjust the settings to match the Lexium MDrive.

If still unable to establish communications, perform a loop back test to identify where in the communications chain the error is occurring.

Loop-back test procedure

  1. Ensure the MDrive product is in a powered down state.
  2. Disconnect the cable from the MDrive communication port.
  3. Add jumpers as shown in the drawings below.
  4. Type characters into the terminal window.
  5. If characters now echo to the terminal screen, there is a communication problem with the Lexium MDrive product.
  6. If typed characters are still not visible, there is a problem with the adapter cable, Motion Control Programmer configuration, or personal computer communication port.

The following diagrams are oriented with the cable end facing the user.

MD-CC404-000 Communication Converters (Lexium MDrive DB9)

FIgure 1: DB9 Loop back

MD-CC200-000 or MD-CC400-001 Communication Converters

Figure 2: IDC loopback wiringiMD-CC402-001 Communication Converter

Figure 3: 10-pin wire crimp (Hirose) loopback wiring

MD-CC401-001/MD-CC405-000 Communication Converter

 

Figure 4: M12 loopback wiring

Party Mode Exception

If the loop back test results indicate a functioning communication link, there is still a chance that the MDrive is communicating properly, but configured in the party mode and you don’t know the device name.

The following command sequence will retrieve the MDrive’s name. There maybe no terminal feedback while typing the characters. Type: [CTRL + J]*PR[space]DN[CTRL + J]. The MDrive should return its name in quotes. Further communication then can be carried out by properly addressing the unit by name. The following command sequence will place the MDrive in the factory default state: [CTRL + J]*FD[CTRL + J]. All parameters will be replaced with the factory defaults and all programs erased. There will be no terminal feedback while typing the reset characters and the SEM copyright sign on message will be the result.

Install the Lexium MDrive Motion Control Programmer

  1. Click the button labeled “Install Motion Control Interface” (1).
    Install MCP
  2. Follow the prompt dialogs to install the application. When completed the button text will change to “Launch Lexium MDrive Motion Control Interface” (2). Click to launch the application.
    Install MCP
  3. The program will open.
  4. Click the tab labeled “Terminal1” (3) to activate the terminal window. Direct (immediate mode) communications will be performed using this tab and the status bar (4).
    Install MCP

Establish Communications

Communications Configuration

  1. With the tab labeled “Terminal1” active, double-click the COM port: BAUD rate (1:9600) field of the status bar (1). This will open the Terminal Preferences dialog. Note: The Terminal Preferences dialog may also be opened using the menu items Edit > Preferences > Terminal Settings.
  2. Select the COM port (2) your communications adapter is installed on.
  3. Verify that the Lexium MDrive default BAUD rate, 9600 kbps, is selected (3)
  4. Click the button labeled “Set” (4). The dialog will close.
  5. Double-click “Port Closed” (5) on the status bar, it should change to “Port Open” (6)
  6. Key in the sequence, CTRL+C (7) or cycle power on the Lexium MDrive.
  7. You should see the sign-on message “Copyright © 2010-2014 Schneider Electric Motion USA” (8) appear within the Terminal1 tab, along with the “>” prompt. This signifies that the device is communicating. You may now send commands and programs to the Lexium MDrive Motion Control device.
Lexium MDriveMDrive

Single interface

Wiring diagram:  Full duplex (4-wire) only

lnd422single
Figure 1: Single Lexium MDrive full duplex point-to-point configuration

 Notes and checkpoints

  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ground is galvanically isolated on the Lexium MDrive
  • If using a pre-made cable, verify wire color to pin location – when in doubt, ring it out

Party mode interface

Party mode is an advanced communications configuration requiring a working knowledge of the ANSI/TIA/EIA-422 and TIA/EIA-485 standards, as well as SEM MDrive products and the MCode programming and control language.

lexium-mdrive-422-multipoint
Figure 2: Lexium MDrive RS-422 multipoint system, bus and stub configuration

Single interface

Wiring diagram:  Full duplex (4-wire) only

Single MDrivePlus/MForce - full duplex connection
Figure 1: Single MDrivePlus/MForce – full duplex point-to-point connection

  Notes and checkpoints

  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ensure the crossover between the interface and Lexium MDrive (Rx—Tx / Tx—Rx)
  • Ground is galvanically isolated on the Lexium MDrive
  • If using a pre-made cable, verify wire color to pin location – when in doubt, ring it out.

Party mode interface

Party mode is an advanced communications configuration requiring a working knowledge of the ANSI/TIA/EIA-422 and TIA/EIA-485 standards, as well as SEM MDrive products and the MCode programming and control language. The diagram below shows a bus and stub type network configuration, MDrive/MForce RD and RL style connectors provide an additional signal contact point for daisy-chain configurations.

MDrive/MForce RS-422 multipoint network
Figure 2: MDrive/MForce RS-422 multipoint network, bus and stub configuration

 

 Causes

The motor power supply input common (GND) is connected internally to the common of the communication port. When two or more units are connected in the party mode, or multi-drop configuration, a “ground loop” is created.

This occurs because the common (communication ground) which connects the communication ports of all connected devices is in parallel with the system power common. This can allow the motor power current to flow through the communication port of another device and vice versa.

Figure 1 shows this recirculation where I1 represents the total current, I2 is return current through the power ground path, and I3 is the current recirculating through the communication ground path.

Recriculating currents in RS-422 multipoint system
Figure 1: Recirculating currents in RS-422 multipoint system
 Solution

Eliminating the recirculating current in this system is accomplished quite easily by:

  • Using an isolated communication converter such as the MD-CC40x-001.*
  • Connecting the isolated ground of the communication converter direct to power ground.
  • Leave the communication ground pin on the device open. Communications will still be grounded via power common without the path for recirculating currents.

Figure 2 shows an example of this connection scheme.

Recirculating currents eliminated
Figure 2: Recirculating currents eliminated
Lexium MDriveMDrive/MForceThird Party

Hardware Installation

Connect the device between the host and Lexium MDrive as shown below. The device is pre-wired and ready to use for a single host-to-LMD connection.

The MD-CC404/5-000 consists of two components:

  1. USB to RS422/485 converter body, which plugs directly into your host computer USB port.
  2. 2 meter (6 ‘) interface cable which will interface to the DB9 (male) connector on the converter to either:
    • Lexium MDrive P3: DB9 (male) connector (MD-CC404-000).
    • Lexium MDrive P3: M12 circular (male) connector (MD-CC405-000).
MD-CC405-000 USB to RS-422/485 Converter

Driver Installation

The MD-CC404/5-000 USB to RS-422/485 Converter is a plug-n-play device, which uses a Virtual COM Port (VCP). Drivers will typically automatically install on an Internet-connected PC notebook or Windows tablet when the device is connected to a free USB port. If automatic installation fails, or if you need to download drivers for a non-connected PC, or for an alternate operating system, the drivers may be downloaded from the web at MD-CC404/5-000 Drivers (FTDI VCP Drivers)

Driver Installation (Automatic)
  1. On an Internet-connected Windows PC or Notebook, plug the MD-CC404/5-000 into an open USB port on your PC.
  2. The device driver software should automatically install.
Driver Installation (Manual)
  1. Download the FTDI VCP Drivers from the FTDI web site will open in a new browser tab).
  2. Follow the instructions located at the FTDI Installation page appropriate to your operating system.
Verify installation (Windows 7/8.x)
  1. Record the COM port number for later use, either from the notification balloon on the lower right of your desktop or from the Windows device manager, accessible by right-clicking on “My Computer” and selecting manage (Windows 7) or by pressing the WIN+X keys on your keyboard (Windows 8).
    Installation successful
    Figure 2: Installation successful
    Computer Device Manager
    Figure 3: Computer Device Manager

You may proceed to the setting up the software and initiate communication with your Lexium MDrive Motion Control step of this tutorial.

Hardware Installation

Connect the device between the host and Lexium MDrive as shown below. The device is pre-wired and ready to use for a single host-to-motion controller connection.

The MD-CC40x-001 consists of three components:

  1. Standard USB cable which plugs directly into your host computer USB port.
  2. USB to RS422/485 inline converter body.
  3. Interface cable which will interface to the P2 connector of the MDrive/MForce product.

The overall length of the cable is 12 feet (3.6 meters).

MD-CC40x-000
Figure 1: SEM USB to RS-422/485 adapters for MDrive and MForce products

Driver Installation

The MD-CC40x-001 USB to RS-422/485 Converter is a plug-n-play device, which uses a Virtual COM Port (VCP). Drivers will typically automatically install on an Internet-connected PC, notebook or Windows tablet when the device is connected to a free USB port. If automatic installation fails, or if you need to download drivers for a non-connected PC, or for an alternate operating system, the drivers may be downloaded from the web at Silicon Labs CP210x USB to UART Bridge VCP Drivers

Driver Installation (Automatic)
  1. On an Internet-connected Windows PC or Notebook, plug the MD-CC40x-001 into an open USB port on your PC.
  2. The device driver software should automatically install.
Driver Installation (Manual)
  1. Download the Silicon Labs CP210x USB to UART Bridge VCP Drivers from the Silicon Labs web site (will open in a new browser tab).
  2. Extract the driver *.zip file to a location on your PC.
  3. Double click the executable file appropriate to your operating system x86 (32-bit) or x64 (64-bit).
  4. Follow the dialogs and prompts to install the drivers.
Verify installation (Windows 7/8.x)
  1. Record the COM port number for later use, either from the notification balloon on the lower right of your desktop or from the Windows device manager, accessible by right-clicking on “My Computer” and selecting manage (Windows 7) or by pressing the WIN+X keys on your keyboard (Windows 8).
Installation successful notification
Figure 2: Installation successful notification
 Computer Device Manager
Figure 3: Computer Device Manager

You may proceed to the setting up the software and initiate communication with your MDrivePlus or MForce.

Installation failure Q & A

Q:  I installed the device, and the driver installation failed. My error message and device manager show the part number “MD-CC400-000”. What do I do?

Installation Error

A: If you see this part number it means that you have an older MD-CC40x. This converter has a legacy device ID and will ONLY function on x86 (32-bit) Windows systems. The legacy drivers and installation instructions may be found at:

Driver Package | Installation Instructions

Q: I only have access to a 64-bit system.

A: Please contact Applications Support for assistance.

The SEM Lexium MDrive product will function with any third party RS-422/485 converter or PC card. See the manufacturer documentation for driver installation. Reference the Hardware: wiring and cabling tab for connection information.

Notes and checkpoints

  • Ensure that the adapter being used is set to 9600 kbps, the default BAUD rate for Lexium MDrive products.
  • Ensure that full duplex (RS-422) is used to communicate with single units, half duplex (RS-485) will only function in multi-drop mode.

Configuring the MDrive

With a comm converter and the MDrive units you plan to use in Party Mode at hand, perform the following:

  1. Connect in single mode RS-422 and initiate communication, download any programs if required.
  2. Assign a device name (DN=”<A-Z, a-z or 0-9>”) i.e DN=”A”.
  3. Set the party flag to 1 (PY=1).
  4. Press CTRL+J to activate party mode.
  5. Type in [Device Name]S and press CTRL+J (Saves the DN and Party Configuration) i.e. AS CTRL+J.
  6. Remove power and label the drive with the assigned DN.
  7. Repeat for each system MDrive.
Wiring RS 422 Multidrop system
Wiring an RS 422 Multidrop system

Terminating the cable

Under 15 ft we recommend that no termination is used. Over 15′ (4.5 meters) The value of capacitance should be calculated using the formula above to find the cable round trip delay divided by the characteristic impedance of the cable (Zo).