External Data Ready [EDR] (Digital488: Pin 46
Digital488/32/OEM: Pin 36)
The
External Data Ready
[
EDR
] line is an edge sensitive input which is used to latch input data. It is used
in conjunction with the
Data Ready
command (
R1
). The
EDR
signal must be at least 1 microsecond wide
and must have a rise and fall time of less than one microsecond. The
EDR
line is normally rising-edge
sensitive but can be programmed with the
Invert
command (
I32
) to be falling-edge sensitive.
Refer to the following diagram for timing relationships.
When using the
EDR
line with the
R1
command, data is not read when the
Digital488
is addressed to talk
as with
R0
. The
Digital488
will only output data when the
EDR
line transitions.
EDR
is not functional in the high-speed binary (
F5
) format.
Inhibit (Digital488: Pin 44
Digital488/32/OEM: Pin38)
The
Inhibit
output is asserted while data on the selected I/O port is being read into the I/O port buffer.
This line is normally active high but may be programmed active low by the
Invert
command (
I1
).
The
Inhibit
line can be programmed independent of any I/O operations with the
Inhibit
command (
Qn
)
.
Refer to the following diagram for timing relationships.
The
Inhibit
line is asserted once for each data read operation for all format [
Fn
] modes except high-speed
binary [
F5
]. In this mode, it is asserted for the first data read after the
Digital488
is addressed to talk.
On the last data-byte transfer, the data is read again with
Inhibit
asserted in anticipation of another data
transfer. If
Inhibit
is used to sequence external hardware, you should be aware that this line will pulse N+1
times; where N is the number of total (5 byte) data transfers.
Timing Diagram for EDR Input and Inhibit Output
Trigger (Digital488: Pin 43
Digital488/32/OEM: Pin34)
The
Trigger
output is pulse for approximately 50 microseconds after a
GET
(Group Execute Trigger)
command is received from the bus controller. The trigger pulse is normally active high, but can be made
active low with the
Invert
command (
I2
). The
Handshake
command (
H2
) can independently pulse the
Trigger
line, independent of any bus activity.
Timing Diagram for Trigger Output
2-6, Getting Started
11-19-01
Digital488 User’s Manual
Содержание Digital488
Страница 21: ...2 10 Getting Started 11 19 01 Digital488 User s Manual...
Страница 37: ...3 16 Command Descriptions 7 17 01 Digital488 User s Manual...
Страница 45: ...Digital488 Mother Board Component Layout 5 2 Service Information 916895 Digital488 User s Manual...
Страница 48: ...Digital488 32 OEM Component Layout Digital488 User s Manual 916895 Service Information 5 5...
Страница 49: ...Digital488 OEM Component Layout 5 6 Service Information 916895 Digital488 User s Manual...
Страница 51: ...5 8 Service Information 916895 Digital488 User s Manual...
Страница 61: ...B 8 Notes...
Страница 62: ...Appendix C Digital488 OEM Mechanical Dimensions Board Dimensions C 1...
Страница 63: ...IEEE Connector Mounting and Hole Punch Out C 2...