User guide

SATELLINE-3AS NMS / NMS Epic / NMS 869 / VHF

User Guide, Version 1.0

5.5

Serial interface, data format

The table below shows the available options for selected DATA port. The NMS port has fixed

settings.

The serial interface uses an asynchronous data format. One character to be transmitted

contains a start bit, the data bits (defining the specific character in question), an optional parity

bit and one or two stop bits. Therefore the overall length of one character is 10 or 11 bits. This

should be taken into account when calculating the data throughput capability of a system. A

useful rule of thumb is that the transmission of one character will require roughly one

millisecond (1 ms) with data transfer speed of 9600 bps.

Start Data Parity End

Picture 5.3.

Asynchronous character data format on the serial line

Example:

With an 8-bit data character length and taking, for example, a decimal value of

”204”, (corresponding to a binary value of ”11001100”) and with a start bit value of ”0”,

parity bit set to either “NO” (NONE), ”0” or ”1” and with a stop bit value of ”1”, the possible

combinations are listed in the table below:

DATA FORMAT CHARACTER (binary value) CHARACTER LENGTH (total)

8 bit, no parity, 1 stop bit 0110011001 10 bit

8 bit, even parity, 1 stop bit 01100110001 11 bit

8 bit, odd parity, 1 stop bit 01100110011 11 bit

8 bit, no parity, 2 stop bits 01100110011 11 bit

8 bit, even parity, 2 stop bits 011001100011 12 bit

8 bit, odd parity, 2 stop bits 011001100111 12 bit

The radio modem serial port settings and the terminal device connected to it must have equal

data port settings (data speed, character length, parity and the number of stop bits.

The serial port settings can be changed in the

Programming Mode

or via LCD display.

Table 5.1.

Possible DATA port and the NMS port configurations.

Port Data speed Characters Parity Stop bits

DATA 1200

2400

4800

9600

19200

38400 bps

7 or 8 bit data None, Even or Odd 1 or 2

NMS 9600 bps 8 bit data Even 1

Note:

300 or 600 bps data speeds nor 9-bit data are not supported!