Serial Connection

Overview

This Guide will provide the necessary information to create and configure a Serial Port in ACM using the default Form view.

Supported Ports

To utilize Serial communications, both the device and host machine must have an available serial port. More than one ACM port object can use the same hardware communications port. For example, two ACM port objects named Serial1_Fast and Serial1_Slow can be created and configured to use COM1 on the host machine. However, Serial1_Fast can be configured to use 38400 baud rate and Serial1_Slow can be configured to use 9600 baud rate. Any devices that are configured in ACM can use either of these logical ports. This allows multiple communication settings to be used on a single hardware communications port.

Even though multiple ACM port objects can use a single hardware communications port, only one device can be polled through the hardware communications port at a time.

Configuration

Once a port has been added to the ACM server, the port must be configured by editing the created object. Configuration may be accomplished using the default Form view.

See the General Object Configuration guide for assistance configuring the General tab. See the Common Port Configuration guide for assistance configuring the Options tab.

Port Tab

Port Number

The COMM port number. Default = 1.

Port Control

The method used to determine exclusive control of the connection.

Maintain Control (Default) - The hardware serial port is acquired by the ACM port object and held open even when not polling. This prevents the port from being used by other applications, but it allows ACM to receive incoming unsolicited data if field devices are capable of initiating communication.
Release When Done - The hardware serial port is acquired by the ACM port object when a poll is due and then released when the poll is complete. This allows other applications to access the port if necessary.

Port Release Delay

The length of time in milliseconds to keep control of the port after communication is done.

Port Options

Lazy Connection. Select to prevent ACM from attempting to re-establish the connection before the next poll.

Baud Rate

Default = 9600.

Data Bits

Default = 8.

Stop Bits

Default = 1.

Parity

Default = None.

Enable Dialup Modem

Select to use a modem when communication through this port.

Flow Control Tab

Flow Type

None
Hardware (RTS/CTS)

CTS Timeout

The length of time (in milliseconds) to wait for the CTS signal after raising RTS. Default = 1000.

Key Down Delay

The length of time (in milliseconds) to hold RTS high after all data has been transmitted. Default = 50.

Key Up Delay

The length of time (in milliseconds) to wait to transmit data after receiving the CTS signal. Default = 50.

Abort if CTS is high

Do not transmit if CTS is already asserted.

Always Assert DTR

Always keep the DTR line high.

Always Assert RTS

Always keep the RTS line high.

Send if No CTS

Transmit even if CTS is not detected before the time out.