© Associated Research 2017
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Appendix D - Remote BUS Interface: USB
This section provides information on the proper use and configuration of the bus remote interface. The USB remote interface is
standard. The IEEE-488 interface included conforms to the requirements of the IEEE-488.2 standard.
USB Interface
Communications Port Configuration
The COM port should have the following configuration:
• 38400 baud
• 8 data bits
• 1 stop bit
• No parity
This interface does not support XON/XOFF protocol or any hardware handshaking. The controller should be configured to
ignore the handshaking lines DTR (pin 4), DSR (pin 6) CTS (pin 8) and RTS (pin 7). If the port cannot be configured through
software to ignore these lines the handshake lines should be jumpered together in two different sets. Pins 4 and 6 should be
jumpered together and pins 7 and 8 should be jumpered together at the controller end of the cable.
Sending and Receiving Commands
Sending Data
Once a command is sent to the instrument over the USB the instrument will send one of two responses. If the transfer was recog-
nized and completed the instrument will return with 06 hex or 6 decimal, the Acknowledge (ACK) ASCII control code. If there is
an error with the command string that is sent, the instrument will respond with 15 hex or 21 decimal, the Not Acknowledge (NAK)
ASCII control code. The ACK or NAK response allows for software handshaking to monitor and control data flow.
Receiving Data
When requesting data from the instrument it will automatically send the data back to the controller input buffer. The controller
input buffer will accumulate data being sent from the instrument, including the ACK and NAK response strings, until it has been
read by the controller.
USB Interface Command List
USB Responses
The USB bus will automatically send any response back to the controller’s input buffer.
Queries and Responses
The HYAMP bus will not send any data to the controller without being queried.
Rules for Sending Commands to the Instrument
The following conventions are used to describe the commands syntax for HYAMP:
• Braces ({ }) enclose each parameter for a command string.
• Triangle brackets (< >) indicate that you must substitute a value for the enclosed parameter.
• The Pipe ( | ) is used to separate different parameter options for a command.
• The command and the parameter data must be separated with a space.
• Each command string should be terminated by the ASCII control code, New Line (NL), (OAh) or the end of line (EOL)
message.
• All commands that end with a question mark (?) are query commands and required an IEEE-488 read command to retrieve
the data from the device’s output buffer.
