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Publication No. 980938 Rev. K
Model T940 User Manual
Astronics Test Systems
DR7 Driver/Receiver Board F-5
Control Logic
The control logic contains the registers, memory and logic that allow the
digital board to interface and configure the hardware.
Signal Descriptions
I/O CONTROL
Signals used to control isolation, termination, NV data and
load relays
MP SIG
Multi-Purpose signal from the data sequencer.
CBUS
An internal Control Bus connecting the digital board to the
Driver/Receiver board.
MF SIG
Multi-Function signal output to the PWR connector.
Firmware & NV Data
The Control Logic firmware is loaded via a serial PROM on power up or VXI
Reset. The firmware is field upgradeable using our supplied loader utility.
Nonvolatile data (serial number, assembly revision is stored in an on-board
EEPROM.
Signal Descriptions
I/O CONTROL
Signals used to program firmware and NV DATA.
DR7 Characteristics
Table F-1: DR7 Characteristics
Description
Characteristics
Digital I/O Type
RS-422/485 (SN75ALS176)
Channels
32 differential per Driver/Receiver board
Output Voltage
V
OL
: 3.0 V (max)
V
OH
: 2.0 V (min)
Differential Input Voltage
200 mV min.±6 V max.
Hysteresis
60 mV
Output Drive Current (typical)
Source/Sink: ± 60 mA
I/O Impedance
100 Ω in parallel with 20K pull-up/pull-down
bias resistors to establish a True level if
unconnected.
Output Skew (Channel-to-Channel)
< 3 ns (drive and compare)
Input Skew (Channel-to-Channel)
< 3 ns (drive and compare)
Auxiliary I/O Channels
(per Driver/Receiver board)
RS-422/485 (4), Differential (with 20K bias
resistors)
TTL (4), Single-ended
ECL (4), Single-ended or Differential
AUX I/O is bi-directional