User Manual

3-9
Part No. 001-2100-101
DTR Enable
The DTR field allows the user to select whether the DTR (Data Terminal Ready) line of the RS-232 port is
asserted when the port is open for the Primary and Secondary COM ports.
Mode
Mode allows the user to select the communications mode for the Primary and Secondary COM ports. See Table 3-
2 for available modes.
Sync/Esc Framing
A typical Sync/Esc frame resembles the following character stream:
SYNC ML Data0 --- DataN Chksum
8 bits 8 bits 8 bits --- 8 bits 8 bits
with the following definitions made:
Sync (8 bits) - marks the start of a frame when not preceded by an ESC character. When using a Sync/Esc
(Framing) Mode, the Field Programming Software will stuff this character automatically.
ML (8 bits) - the length of the frame. ML is the number of characters left to be received including the checksum
but excluding any ESC characters added as part of the protocol. When using a Sync/Esc (Framing) Mode, the Field
Programming Software will stuff this character automatically based on the number of Data Characters.
Data 0 - N(8 bits each) - frame information
Chksum (8 bits) - the 8 bit 2s complement of the sum of the frame less the SYNC character and any additional
ESC added characters ignoring the carryout of the high order bits. When using a Sync/Esc (Framing) Mode, the
Field Programming Software will stuff this character automatically.
Table 3-2 Communications Modes
Mode Description
Sync/Esc with No HS Send data using the Sync/Esc byte-stuffing protocol with no handshaking
Buffered with No HS Send buffered data without handshaking
Sync/Esc with RTS/CTS HS Send data using the Sync/Esc byte-stuffing protocol with RTS/CTS
hardware handshaking
Buffered with RTS/CTS HS Send buffered data with RTS/CTS hardware handshaking
Sync/Esc with Flow Control HS Send data using the Sync/Esc byte-stuffing protocol with flow control
handshaking
Buffered with Flow Control HS Send buffered data with flow control hardware handshaking