Epson MFJ-1278B manual Rxblock ON/OFF, $Ff, Pid, Data

MFJ-1278B MULTI-MODE	OPERATIONAL COMMANDS
RXBLOCK ON/OFF	Mode: Packet	Default: OFF
Parameters:

ON The MFJ-1278B will send data to the terminal in RXBLOCK format.

OFF The MFJ-1278B will send data to the terminal in standard format.

The RXBLOCK command is designed for automated operations, such as packet bulletin board stations. It is intended to help such systems discriminate between data received from the connected station and MFJ-1278-generated messages.

Correct operation of RXBLOCK is dependent on the AWLEN parameter getting set to 8 (bits) since the character FF hex marks the beginning of a received data unit header.

When RXBLOCK is ON, data from other stations will be sent from the MFJ-1278B in the following format:

*$FF*	L0.....L1	PID		DATA
{ prefix }	{ length }	{ pid }	{	data	}

The fields above are defined as follows:

prefix	$FF	A character with all 8 bits set
length	L0	The high order length of the data, length, and pid fields logically ORed
	with the value $F0
	L1	The low order length of the data, length, and pid fields
pid	PID	The Protocol IDentifier byte received for the following data field
data	DATA	[Optional], variable length data

For best operation it is suggested that parameters like AUTOLF, MFILTER etc. be set OFF in order to prevent uncertainties in the size of the data field.