Operation: Computer Programming

Every Ultra-high performance high stability add-on module has the following communication connections available:

Interface	Location	Connector	Standard/Optional	Priority
USB (Host)	Front	JR1	Standard	1
USB (Host)	Rear	JR2	Standard	2
RS485	Rear	JR3	Standard	5
LXI TCP/IP Ethernet	Rear	JR6	Optional	3
IEEE-488 GPIB	Rear	JR6	Optional	3

All of the communication connections share the same internal communications bus; only one communication interface can be used at a time. The front panel menu display will always show what communication interface is active. The DBx Module Add-On

The front panel USB takes the highest computer interface priority. When a front or rear USB connection is physically made the DBx Module Add-On will automatically switch to computer control from RS485 to the newly connected USB port. Conversely, when a command is sent via the optional LXI TCP/IP Ethernet or IEEE-488 GPIB interface, the DBx Module Add-On will automatically switch to computer control from the Ethernet or GPIB port with the new communication. Switching back to USB requires disconnecting and reconnecting the USB plug or power cycling the DBx Module Add-On. RS485 is the lowest priority interface and only has control when the USB ports are disconnected and the there is no communication over LXI TCP/IP Ethernet or IEEE-488 GPIB interfaces.

Communications Validation

It is import to establish and validate basic communications functions before starting a sophisticated computer interface project. The following instructions are intended to help customers isolate problems with computer settings, wiring, and electrical noise. The validation instructions also provide a common environment for which Magna-Power can reproduce issues in support cases and better serve the customer.

If not already installed, Magna-Power Electronics recommends using the terminal emulation programs called PuTTY for creating serial connections.

USB Communications Validation

USB uses serial communications. To test, make a physical connection between the USB Type B connector on the DBx Module Add-On and the USB Type A on the computer. Pin outs for these connectors are described in USB Interface. Connect using the standard USB cable included with the product. The front panel shows the active state of the communications interface. If the front USB was connected, the display should transition from RS485 to USB2. If the rear USB was connected, the display should transition from RS485 to USB1. After a physically connection is made a session connection is made with the DBx Module Add-On.

Open Device Manager and under ports make note of the COM port number, as shown in fig-programming-devmanager.

Window Device Manager

Open PuTTY and select the Session menu. Enter the COM port that was found in Device Manger and enter 115200 for the Speed. Set the Connection type to Serial, as shown in fig-programming-putty-comm.

PuTTY Session Settings

Select the Terminal menu and set Force on for all options. Press the Open button to start the communications session with the DBx Module Add-On, as shown in fig-programming-putty-echo.

PuTTY Terminal Settings

Session should open a new blank window. Type the command:

*IDN?

If settings match and wiring connections are correct, the session window should look like fig-programming-putty-scpi.

PuTTY Terminal Session Output

RS485 Communications Validation

RS485 also uses serial communications. Most customers will need a USB-to-RS485 adapter (not included) to allow the computer to connect to RS485. Any RS485 adapter should work provided it supports half-duplex communication and 115200 baud. Magna-Power Electronics recommends USB-COM485-PLUS1 and USB-COM485-PLUS4 adapters from FTDI. The adapter will serial port(s) in Windows Device Manager.

Customers will also need to create their own cable. The DBx Module Add-On interfaces to RS485 through a RJ45 connector located in the rear. RJ45 mates readily with Category 5 Ethernet cables. When crimping wires to the connector make sure to follow the pins outs described in RS485 Interface.

By default, the RS485 interface is active when no other communication interface cables are connected. The front display will always show the RS485 state even when the wire is disconnect. Once the computer and DBx Module Add-On are physically connected, open PuTTY, and follow the instructions described in USB Communications Validation to make a serial connection and test it.