Measurement Computing Digital488/80A - Manual (Page 65)

I - Invert
SYNTAX Ival Define the polarity of the handshake and data lines, where 000
≤
val
≤
127 , as
summed from the following states:
•
0 - (Default) All handshaking/control lines are active high,
all data lines are high true.
•
1 - The Inhibit output line is active low.
•
2 - The Trigger output line is active low.
•
4 - The Data Strobe output line is active low.
• 8 - The Clear output line is active low.
• 16 - The Data lines are low true.
•
32 - The EDR input line is falling-edge sensitive.
•
64 - The Service input line is falling-edge sensitive.
I? Returns the last Invert command executed.
Note: The Invert commands are OR ed together as received. To delete any one
command, it is necessary to program the default mode I0 , then reprogram the
desired commands.
DESCRIPTION
The Invert (
I ) command is used to change the polarity of the handshaking and data lines. At power-up, all
handshaking/control lines are active high (logic 1 = +5 volts). The Invert command can selectively change the polarity
of each of the handshaking/control lines, and the polarity of the set of data lines. If multiple Invert commands are
contained within the same string, an Execute (
X ) command should be included at the end of each Invert command. An
alternative is to add up the values of each Invert command desired, and send a single command with the sum of the
desired commands. The Invert commands are
OR ed together as received. To delete any one command, it is
necessary to program the default mode I0 , then reprogram the desired commands.
EXAMPLE 1
PRINT#1,"CLEAR08" Line 1: Reset the Digital488/80A.
PRINT#1,"OUTPUT08;I32X I64X" Line 2: Select the EDR and Service input lines as falling-edge sensitive.
EXAMPLE 2
PRINT#1,"CLEAR08" Line 1: Reset the Digital488/80A.
PRINT#1,"OUTPUT08;I96X" Line 2: Performs the same function as the Invert command string in
Example 1.
Digital488/80A User’s Manual 967695 Digital488/80A Commands 59