53A-425 – QUAD ARINC 429 Transmitter Card
OPT 33 – Modified Outputs Channels 1 through 4
OPT 35 – Low Output level 3.5V
53A-746 – Data Cable. or
53A-780 – Hooded Connector

• Four independently programmable ARINC 429 transmitter channels
• Converts 8-bit bytes to 32-bit Mark 33 DITS serial words
• Real-time input capability allows data to be modified “on-the-fly” without interrupting the transmission sequence
• May be programmed to transmit illegal data formats and voltages for worst-case testing of receivers

The 53A-425 Quad ARINC 429 Transmitter provides four channels for testing and transmitting information onto the Mark 33 DITS (Digital Information Transfer System) used on many civil aircraft. The four independent transmitters each have an associated buffer memory for storing up to 32,768 ARINC 429 words. (Each ARINC 429 word is four bytes long.)

Data can be updated “on-the-fly” without interrupting the transmission sequence of the 53A-425 Card. Data in memory is organized into frames; each frame consists of a header and one or more data words. The header word controls the time interval between the start of one frame and the start of the next frame. The header word also controls parity, word length, and inter-word gap in order to allow word format protocol to be tested on a frame-by-frame basis.

Output voltage level may be programmed for each channel, as can the transmit bit rate. In addition. the Card can read back to the system controller the address of the last ARINC 429 word transmitted and the error code of any errors encountered during programming or self test.

Built-In-Test Equipment (“BITE”) for the 53A-425 Card is provided by an extensive self test capability that permits a wrap-around check for each channel by reading the data back just before the output amplifier. In addition, five status LEDs indicate the transmit status of each channel and any errors encountered during self test or programming.

Four independent ARINC 429 Transmit Channels.

Intel Model 80186.

Connects directly to the DITS Mark 33 bus.

128 KBytes of memory associated with each channel, used to store messages (data) and control instructions.

Programmable odd or even on a frame-by-frame basis for each channel

DITS Word Format
Programmable for 31-, 32-. or 33-bit word on a frame-by-frame basis for each channel

lnterword Gap:
Programmable for 2- or 4-bit times between words on a frame-by-frame basis for each channel

Frame lnterval (the time delay between the start of one frame and the start of the next frame):
Programmable from 5 msec to 4 sec in 1 msec steps on a frame-by-frame basis for each channel.
Delay Accuracy. ±150 µsec single channel transmitting; ±500 µsec all channels transmitting.

Bit Rate Period:
Programmable for each channel from 8 µsec to 8.19 msec in 250 nsec steps (122 Hz to 125 KHz).

Can be programmed for each channel on a frame-by-frame basis to indicate the start of each frame.

External Clock Input (each channel):
Type, TTL.
Range, 0 to 125KHz square wave.
Loading. 1 TTL load equivalent.

ARINC 429 Output
Type. differential.
Voltage Levels (programmable):
Rise/Fall Time:
16 to 125 Kbits per sec, 1.5 ±0.5 µsec.
0 to 16 Kbits per sec. 100 ±5 µsec

Output Impedance, 75 ±5 Ohms balanced.
Drive Capability, 20 ARINC 429 receivers (400 Ohm max load).

Programmed By:
ASCII Characters, or ASCII Characters followed by binary data bytes.

Recommended Cables:

Available Options:
OPT 33, modified outputs channels 1 through 4.
OPT 35, low output level 3.5V