2.2.2.4 Power-On Default Settings
Switches S4 and S5, labeled PTO Default, set the power-on default settings for the
Digital488HS/32. The power-on settings set the output port to high or low on power-
on.
1 2 3 4 5 6 7 8
OPEN
S5
OUT
0
1
2
3
4
5
6
7
HI
LO
PTO DEFAULT
1 2 3 4 5 6 7 8
OPEN
S4
OUT
8
9
10
11
12
13
14
15
HI
LO
PTO DEFAULT
Power On Default Switches for First Byte and Second Byte
At power-on, iRESET, Device Clear or Selected Device Clear, S3-6 (output data
polarity) is ignored and the digital outputs are forced to the level selected by the S4
and S5 settings. These settings are in effect until the first datum is written to the
output port. Each data line in the output port is set individually by these switches.
Factory default is all data lines low. The oEND output is forced active.
2.3 External Switches
The Digital488HS/32 has one eight position switch accessible fron the rear panel.
This switch determines the unit's IEEE 488 bus address, input and output mode, and
whether NDAC Holdoff is used. The switch is read only during power on and should
be set before applying power.
2.3.1 Input Port Mode Selection
The switch labeled MODE IN selects either 8-bit or 16-bit input port operation. In 8-
bit mode, 8-bit data are transferred from the second byte port with the iEND line
driving the IEEE 488 bus EOI line as the ninth bit. In 16-bit mode, the first eight bits
of data are transferred from the first byte port followed by the next eight bits with
iEND from the second byte port. The user connects the external device to correspond
to the desired byte ordering (most significant byte first or least significant byte first).
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