GE PACSystems RX7i Reference Manual page 138

Port Parameters
Data Rate (All Port Modes, except Available.) Data rate (bits per second) for the port.
Choices: 1200 Baud, 2400 Baud, 4800 Baud, 9600 Baud, 19.2k Baud, 38.4k Baud, 57.6k Baud,
115.2k Baud.
Default: 19.2k Baud.
Data Bits (Available only when Port Mode is set to Message mode or Serial I/O.) The number of bits in a
word for serial communication. SNP uses 8-bit words.
Choices: 7, 8.
Default: 8.
Flow Control (RTU slave, Message Mode, or Serial I/O.) Type of flow control to be used on the port.
Choices:
▪
▪
Default: None.
Note:
Parity (All Port Modes, except Available.) The parity used in serial communication. Can be changed if
required for communication over modems or with a different SNP master device.
Choices: None, Odd, Even.
Default: Odd.
Stop bits (Available only when Port Mode is set to Message Mode, SNP Slave or Serial I/O.) The number of
stop bits for serial communication. SNP uses 1 stop bit.
Choices: 1, 2.
Default: 1.
Physical (All port modes except Available.) The type of physical interface that this protocol is
Interface communicating over.
Choices:
▪
▪
▪
Default: 4-wire Transmitter On.
Turn Around (Available only when Port Mode is set to SNP Slave.) The Turn Around Delay Time is the minimum
Delay Time time interval required between the reception of a message and the next transmission. In 2-wire
(ms) mode, this interval is required for switching the direction of data transmission on the
communication line.
Valid range: 0 through 2550ms, in increments of 10 ms.
Default: 0.
Timeout(s) (Available only when Port Mode is set to SNP Slave.) The maximum time that the slave will wait
to receive a message from the master. If a message is not received within this timeout interval,
the slave will assume that communications have been disrupted, and then it will wait for a new
attach message from the master.
Valid range: 0 through 60 seconds.
Default: 10.
GFK-2222AD
For Serial I/O Port Mode: None, Hardware, Software (XON/XOFF).
For all other Port Modes: None, Hardware.
The Hardware flow-control is RTS/CTS crossed.
2-wire: There is only a single path for receive and transmit communications. The receiver
is disabled while transmitting.
4-wire: There is a separate path for receive and transmit communications and the
transmit line is driven only while transmitting.
4-wire Transmitter on: There is a separate path for receive and transmit
communications and the transmit line is driven continuously. Note that this choice is
not appropriate for SNP multi-drop communications, since only one device on the multi-
drop line can be transmitting at a given time.
April 2018
Chapter 3. CPU Configuration
127