The RTX1553/SPA-MT Serial Port Adapter is a powerful, dual channel, MIL-STD-1553 bus Monitor Terminal (MT) housed in a box about twice the size of a quarter. The Adapter attaches directly to any PC’s RS232 port or USB port via a converter. It requires no batteries nor external power. It derives all its power from the RS232 lines, although, if preferred, it can be externally powered. The MIL-STD-1553 communication protocol is implemented in firmware using a state of the art FPGA. The RTX1553/SPA-MT is very small and can easily be moved from a PC to a laptop and back. For Windows users, the RTX1553/SPA-MT comes with an extensive software API library with detailed documentation.

The RTX1553/SPA-MT device Architecture
The RTX1553/SPA-MT has high input impedance receivers that convert the MIL-STD-1553 analog signals from the two redundant buses into digital waveforms. The digital signals are processed by the FPGA and the results are sent as a data packet to the PC via the high speed RS232 interface. The transfer speed is programmable up to 1.2Mbaud (when used with a USB adapter). The MIL-STD-1553 protocol is implemented in the firmware of a powerful FPGA. The FPGA performs Manchester decoding, message timing analysis, message protocol integrity and reports results to the PC. Incoming 1553 messages can be filtered on RT address basis and therefore reducing and focusing the data delivered to the PC. Every MIL-STD-1553 message can be time tagged with a high resolution clock. The RTX1553/SPA-MT is configured for direct coupling to the MIL-STD-1553 signal via a DB15 connector. External hardware can be attached when transformer coupling is desired.

Monitor (MT) Features
The protocol processor detects, analyses and reports the following MIL-STD-1553 message types:

•BC to RT,
•RT to BC,
•RT to RT transfer,
•Mode commands, and Broadcast Mode commands

The RTX1553/SPA-MT can be configured to Monitor traffic on bus-A and bus-B and report back which bus is being used. The user may also select to enable bus-A only (disable bus-B), bus-B only (disable bus-A), or enable both A and B. A programmable mask can direct the device to only Monitor traffic from/to any subset of RTs of interest.

Data Reporting
The RTX1553/SPA-MT sends data to the PC over the RS232 communication channel in the form of packets. A packet contains the command issued by the Bus Controller, the response from the Remote Terminal (if required by protocol), all data words associated with the command, a time-tag and a protocol validation tag. Protocol errors and signal integrity errors are indicated in the protocol validation tag. The error types detected and reported by the RTX1553/SPA-MT are:

•Manchester encoding violation
•Word Parity Errors
• Response Time out
•Message size error, including special message size rules for Mode commands
•Broadcast rules violation


For Windows users, RTX provides an extensive software API library as a DLL. The API is fully documented with coding examples and easy to use. It covers all capabilities of the RTX1553/SPA-MT Adapter and releases the programmer from detail understanding of the hardware. RTX Systems offers extensive free support to our customers in their application development / integration effort. RTX offers Navigator, an optional graphical user interface (GUI) software for Windows. Navigator is intuitive and simple to use. It enables the user to exercise all capabilities of the Adapter.


MIL-STD 1553 Monitor
Serial Port Adapter