GE PACSystems RX7i Reference Manual page 139

Chapter 3. CPU Configuration
Port Parameters
SNP ID (Available only when Port Mode is set to SNP Slave.) The port ID to be used for SNP
communications. In SNP multi-drop communications, this ID is used to identify the intended
receiver of a message. This parameter can be left blank if communication is point to point. To
change the SNP ID, click the values field and enter the new ID. The SNP ID is up to seven
characters long and can contain the alphanumeric characters (A through Z, 0 through 9) or the
underline (_).
Specify STOP (All port modes except Available.) Determines whether you accept the default STOP Mode or set
Mode it yourself.
Choices:
No: The default STOP Mode is used.
Yes: The STOP Mode parameters appear and you can select the STOP Mode. If you set the STOP
Mode to the same protocol as the RUN Mode, then the other STOP Mode parameters are read-
only and are set to the same values as for the RUN Mode.
Default: No.
STOP Mode (Available only when Specify STOP Mode is set to Yes.)
The STOP Mode protocol to execute on the serial port. If you set the STOP Mode to the same
protocol as for the RUN Mode, then the other STOP Mode parameters are read-only and are set
to the same values as for the RUN Mode.
Choices and defaults are determined by the Port Mode setting.
■
SNP Slave: Reserved for the exclusive use of the SNP slave.
■
RTU Slave: Reserved for the exclusive use of the Modbus RTU Slave protocol.
If the STOP Mode protocol is different from the Port mode protocol, you can set parameters for
the STOP Mode protocol.
If you do not select a STOP Mode protocol, the default protocol with default parameter settings
is used.
Note:
Turn Around (Available only when STOP 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:
▪
When the STOP Mode is different from the Port Mode: 0ms.
▪
When the STOP Mode is the same as the Port Mode: the value is read-only and is set to the
same value as the Turn-Around Delay Time for the Port Mode.
128
Port (RUN) Mode
RTU Slave
Message Mode
Available
SNP Slave
Serial I/O
Setting the Port Mode to RTU Slave and the STOP Mode to SNP Slave may cause loss of
programmer connection and delayed reconnection when the controller transitions from
STOP to RUN Mode. To avoid this behavior, select SNP Slave for the Port Mode and do
not specify a STOP Mode. For additional details, see RTU Slave/SNP Slave Operation with
Programmer Attached.
PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual
STOP Mode
Choices: SNP Slave, RTU Slave
Default: RTU Slave.
Choices: SNP Slave, RTU Slave
Default: RTU Slave.
Available
(Not supported on CPE302/CPE305)
SNP Slave
Choices: SNP Slave, RTU Slave
Default: RTU Slave.
GFK-2222AD