Interface; Gpib / Rs-232 Interface Command List; Rs-232 Interface - Extech Instruments 7630 Operation Manual

6.2.7 RS-232 Interface

This interface is standard on 7630. This interface provides all of the control commands and
parameter setting commands of the GPIB interface with the exception of the 488.2 Common
Command the Status Reporting commands and SRQ capability. The identification command
*IDN is also available through RS-232.
The RS-232 cabling should be configured as follows for a 9 pin serial port interface:
Instrument RS-232 Port
RD
TD
SIG
GND
The COM port should have the following configuration. 9600 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 can not be configured through
software to ignore the lines then the handshake lines should be jumpered together in two
different sets. Pins 4 and 6 jumpered together and pins 7 and 8 jumpered together at the
controller end of the cable.
When sending command over the RS232 bus the instrument will send a response string of 06
hex or 6 decimal, the Acknowledge (ACK) ASCII control code if the transfer was recognized
and completed by the instrument. 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. 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.

6.2.8 GPIB / RS-232 Interface Command List

A GPIB read command must be sent after the command strings, to retrieve any data from a
query command (?). The 7630 GPIB bus will not send any data to the controller without
being queried. The RS-232 bus will automatically send any response back to the controller's
input buffer. Each command string should be terminated by the ASCII control code, New
Line <NL>, OAh or the end of line EOL message for GPIB.
The following conventions are used to describe the commands syntax for 7630. Braces
({ })enclose each parameter for a command string. Triangle brackets (< >) indicate that you
2
3
5
PC / Bus Controller
2 RD
3
TD
SIG
5
GND
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