IOtech Digital488, Manual

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Digital488 User’s Manual
11-28-01
Introduction, 1-1
Introduction 1
General Description
Digital488
The Digital488/32/OEM is a board level interface with the same capabilities as the Digital488 .
All descriptions in this manual refer to both products unless otherwise stated. When the model number
Digital488 is used in this manual, Digital488/32/OEM is also implied.
The Digital488 is a digital input and output interface to the IEEE 488 bus. Each unit has 40 TTL level
digital I/O lines, which are divided, into 5 eight-bit ports. Each port is software programmable as input
or output. The
Digital488 has several features, which give it versatile interface capability. A trigger output
signal is asserted on the Group Execute Trigger (GET) command. Edge-triggered inputs can generate
a Service Request on the bus. Six data formats are software programmable, including ASCII hexadecimal,
ASCII character, ASCII binary, binary, high speed binary and ASCII decimal.
There are also individual bit set and bit clear commands. Programmable terminators are provided to
facilitate interfacing to various controllers.
A status mode enables the controller to interrogate the programmed status of the Digital488 at any time. A
self-test is initiated at power-on which checks for proper RAM and ROM operation.
When addressed to talk, the Digital 488 will output data from all forty bits or a selected 8-bit port. When
addressed to listen, the unit will input data and programming information from the controller and output the
data to the appropriate I/O port.
Digital488/32/OEM
The Digital488/32/OEM is a 4 in. by 4 in., 32 I/O line interface board for transferring data between the
IEEE 488 (GBIP, HP-IP) bus and devices equipped with up to 32-bit wide digital ports.
The Digital488/32/OEM ’s 32 TTL-level digital I/O lines are programmable in 4-bit ports as either inputs
or outputs. When addressed to talk, the Digital488/32/OEM will output data from all thirty-two bits or a
selected 8 bit port. The board also offers six handshake lines for implementing clear, data strobe, external
data ready, inhibit, trigger, and SRQ functions. Its firmware includes a complete command set for
facilitating the implementation of all its functions. This command set is identical to that employed by the
other board-level and external interfaces in IOtech’s industry-standard Digital488 family, facilitating quick
prototyping and making the
Digital488/32/OEM compatible with other Digital488 family units.