Com1 And Com2 Parameters - GE PACSystems RX7i Reference Manual

Chapter 3. CPU Configuration

3.2.10 COM1 and COM2 Parameters

These parameters configure the operating characteristics of the CPU serial ports
have the same set of configuration parameters. The protocol (Port Mode) determines the parameters
that can be set for each port.
Port Parameters
Port Mode The protocol to execute on the serial port. Determines the list of parameters displayed on the
Port tab. Only the parameters required by the selected protocol are displayed.
Choices:
▪
RTU Slave mode: Reserved for the use of the Modbus RTU Slave protocol. This mode also
permits connection to the port by an SNP master, such as the WinLoader utility or the
programming software.
▪
Message mode: The port is open for user logic access. This mode enables C language blocks
to perform serial port I/O operations via the C Runtime Library functions.
▪
Available: The port is not to be used by the PLC firmware. (The CPE302/CPE305 does not
support this selection.)
▪
SNP Slave: Reserved for the exclusive use of the SNP slave. This mode permits connection to
the port by an SNP master, such as the WinLoader utility or the programming software.
▪
Serial I/O: Enables you to perform general-purpose serial communications by using
COMMREQ functions.
Default: RTU Slave.
Note:
Station (RTU Slave only) ID for the RTU Slave.
Address Valid range: 1 through 247.
Default: 1.
Note:
Note:
68
Not supported by RSTi-EP CPE100/CPE115 at the time of publication.
126
If both serial ports are configured for any protocol other than RTU Slave or SNP Slave,
the RUN/STOP Switch should not be disabled without first making sure that there is a
way to stop the CPU, or take control of the CPU through another device such as the
Ethernet module. The Serial I/O protocol is only active when the CPU is in RUN Mode. If
the CPU can be set to STOP Mode, it will switch the protocol from Serial I/O to the STOP
Mode protocol (default is RTU Slave). If an SNP Master, such as the programming
software in Serial mode, begins communicating on a port, the RTU protocol
automatically switches to SNP Slave. As long as the CPU can be stopped, the protocol of
the port can be auto-switched to one that enables serial programmer connection. Refer
to STOP Mode protocols.
If an Ethernet port is available, you can communicate with the CPU by connecting PME
software via the Ethernet port.
You should avoid using station address 1 for any other Modbus slave in a PACSystems
control system because the default station address for the CPU is 1. The CPU uses the
default address in two situations:
1. If you power up without a configuration, the default station address of 1 is used.
2. When the Port Mode parameter is set to Message Mode, and Modbus becomes the
protocol in STOP Mode, the station address defaults to 1.
In either of these situations, if you have a slave configured with a station address of 1,
confusion may result when the CPU responds to requests intended for that slave.
The least significant bit of the first byte must be 0. For example, in a station address of
090019010001, 9 is the first byte.
PACSystems* RX7i, RX3i and RSTi-EP CPU Reference Manual
68
. COM1 and COM2
GFK-2222AD