Radio modems provide a simple wireless link with the ability to send any message protocol at any data rate up to the maximum quoted. They provide a simple means of passing RS232 data streams with no message overhead in the form of extra addressing or error-checking codes.

The MP2503 modem pcb is designed to operate with Magenta's crystal-controlled Radio Modules. It is a non-intelligent device to provide a serial radio data link primarily for incorporating into OEM's systems.

Serial data supplied to the transmitter input is reproduced at the distant receiver's output. Only when operating near the limit of maximum range will the received output be prone to data corruptions.

The transmitter is switched on by asserting the TXON line high. A short delay is required to allow the transmitter and receiver to establish the link before any data can be sent.

When the transmitter is switched off at the end of a message, a short burst of noise may occur before the receiver's mute operates. This noise should be ignored by the system connected to the receiver.

The user may need to provide error checking and/or addressing to each mesage if the application requires guaranteed data integrity.

Options are available for RS232 or TTL data levels. Another option is available to provide a speech link as well as the data link. This is particularly useful during commissioning of the telemetry system.

Technical Details
General

TX-RX Changeover	<6ms
TX and RX Risetime	<6ms
Data Rate	1200 baud (2400 or 4800 optional-state with order)
Supply Voltage	6-16Vdc (also depends on host radio's supply voltage range)
Dimensions	Fits on top of radio module-adds 7mm to height
Operating Temperature	-30 to +60° C
Humidity	95% RH, non-condensing
Current Consumption	5mA excluding radio

Technical Details
Connections

1	+V	Positive Supply
2	TXON	TX enable, TTL active high
3	TXD	TX data input, RS232 or TTL as specified
4	0V	Ground, negative supply
5	RXD	RX data output, RS232 or TTL as specified
6	/CD	RX carrier detect, TTL active low
7	RXON	RX enable, TTL active high