Measurement Computing Serial488/4 - Manual (Page 57)

Section 3 Command Descriptions
3.18
Break Qn
The Break command enables or disables the sending of break (a constant
stream of '0' bits) by the selected port . While a port is sending break no characters
can be transmitted. When sending break is subsequently disabled, normal character
transmission will resume. The factory default setting as set by the Save Configuration
command (S0) is Q0, disable sending break.
Q0
Disable sending break.
Q1
Enable sending break.
Q?
Return current break setting.
NOTE: The programmer must ensure the break command is enabled for more than
one character time before issuing the disable sending break command to ensure that
break is recognized.
NOTE: Sending a break w hile a port is transmitting data may cause the character
currently being transmitted to become corrupted. The Output Query (O?) may be used
to verify that the serial output buffer is empty. Once the serial output buffer is empty
a delay of two character times is required to ensure that all serial data has been
transmitted and will not be corrupted by sending break.
Example 1: Program port 1 to send a break using dual primary addressing mode
PRINT#1,"CLEAR08"
reset the Serial488/4
PRINT#1,"OUTPUT08;P1X"
select port 1 as the current port
PRINT#1,"OUTPUT08;Q1X"
send break
FOR LUP = 1 to 100:NEXT LUP
delay a short while
PRINT#1,"OUTPUT08;Q0X"
stop sending break
Example 2: Program port 3 to send a break using secondary addressing mode
PRINT#1,"CLEAR0800"
reset the Serial488/4
PRINT#1,"OUTPUT0800;P3X"
select port 3 as the current port
PRINT#1,"OUTPUT0800;Q1X"
send break
FOR LUP = 1 to 100:NEXT LUP
delay a short while
PRINT#1,"OUTPUT0800;Q0X"
stop sending break