Connection Settings

Overview

A Connection Settings object is used to configure timeout, delay, and modem information for ports and/or devices. A single Connection Setting object can be shared across multiple devices and ports.  Often, default options will work in the Connection Setting object.

By default, a device will use the Connection Settings of its Port object.  If the device has a separate connection setting associated, it will override the connection settings of its port. This allows ports to be configured with commonly required settings, but also allows devices with specific needs, such as a longer reply timeout, to override the port settings.

Configuration

Connection Settings Tab

Poll Cycle Settings

A Poll Cycle is the set of read and/or write messages for a given device that are transmitted and processed when:

• A schedule comes due
• A demand poll is performed
• The "Retrieve History" command is manually executed

Poll Retries

• Default = 2. The number of times a Poll Cycle can be attempted.  It applies to scheduled and non-scheduled Poll Cycles.
  • If a valid response is received for all messages in the Poll Cycle, it is considered complete.  ACM will then move on to the next device handled by that port.
  • If one or more messages has the state "No Response" and the number of poll retries has not been reached, the Poll Cycle is considered incomplete and is placed into the retry queue for that port.
  • If all Poll Cycle Retries are incomplete, the Poll Cycle is considered failed and the message "{Device Name} no more retry delays" will appear in the logger.

Fail Delay

• Default = 30. The Fail Delay is used to lengthen the minimum period of time that must elapse between Poll Retries.  It applies to scheduled Poll Cycles only. 
  • If there are many incomplete Poll Cycles for the port, the retry queue may grow causing the time period between Poll Retries to lengthen.
  • Note: Incomplete Poll Cycles for non-scheduled events will be processed when they reach the front of the queue, whether the Fail Delay time has elapsed or not.

Poll Message Settings

A poll message is a single read or write message.

Message Retries

• Default = 2. The number of times a single message can be sent.
  • If a valid response is received, the next message in the Poll Cycle will be sent.
  • If a valid response is not received and the number of message retries has not been reached, the message will be sent again
  • If a valid response is never received for the message, the message state will be set to "No Response" and ACM will move to the next message in the cycle unless "Abort Poll After First No Response" is checked in which case the Poll Cycle is considered "incomplete".

Reply Timeout (in milliseconds)

• Default = 2000. This is the length of time ACM will wait for the entire response to be received before setting the message state to "Incomplete" if there are retries left, or to "No Response" if not.  I.e.  After a message is sent, there are X number of milliseconds that may pass without a complete response before ACM considers the message failed. 

Initial Timeout (in milliseconds)

• Default = 0 (disabled). This is the length of time ACM will wait for the first byte of the response to be received before setting the message state to "Incomplete" if there are retries left, or to "No Response" if not.  I.e.  After a message is sent, there are X number of milliseconds that may pass without any response before the ACM considers the message failed.  If this setting is 0, no initial timeout is applied. 

Inter-Character Timeout (in milliseconds)

• Default = 0 (disabled). This is the length of time ACM will wait between bytes before considering setting the message state to "Incomplete" if there are retries left, or to "No Response" if not.  I.e.  When a byte is received, there are X number of milliseconds that may pass without receiving any more bytes before the ACM considers the message failed.  If this setting is 0, no inter-character timeout is applied.
• Common usage: This property is useful with a slow connection where only a few bytes of data are received at a time. In that scenario, the Reply Timeout given a lengthier time period to ensure the port waits for the full response if it continues to receive data bytes. If more time passes between received bytes than the value in the Inter-Character Timeout field, ACM will consider the message failed at that time instead of waiting the duration of the "Reply Timeout".

Skip Retries on Failed Devices

A "failed device" is a device for which all poll cycle retries failed.

• Default = Not selected. This setting determines whether or not to attempt all poll retries for a failed device on subsequent poll cycles.
  • When this option is not selected, there is no change to the "Poll Retry" behavior explained above. 
  • When this option is selected, ACM will only attempt the poll cycle one time, disregarding the "Poll Retry" count until the device has a successful poll.

• Common Usage:  This property is useful to prevent extra polls when devices are known to be offline

  Enabling this option for devices on poor communication links may result in failure to collect data.

Abort Poll After First No-Response

Default = Not selected. This option applies to how the Poll Cycle processes message if a single message's state is setting the message status to "No Response".  Without this selected, a Poll Cycle will continue to process all messages in the cycle, ignoring message states.  When it is selected, no more messages in the Poll Cycle will be sent after a single message with state "No Response" and will be considered "incomplete".

Dialup Modem Tab

Command Retries

The maximum number of tries to issue a modem command with no response before continuing to another poll. Default = 2.

Command Timeout

The maximum amount of time in seconds to wait for the modem to respond.  Default = 2

Connect Timeout

Maximum amount of time in seconds to wait for the modems to establish a connection.  Default = 35.

Dial Prefix

The modem dial prefix.  Use ATDT for tone dialing, ATDP for pulse dialing or another custom setting.  Default = ATDT.

Connect String 

The string returned by the modem to indicate a connection to a remote modem.  Default = CONNECT.

Hangup String

The command string to hang up the modem and terminate the call.  Default = ATH0.

Modem Initialization

The initialization string used to configure the modem.  Default = ATE0Q0&C1&D2&S1V1X4.

Warmup Delay

The time to wait in milliseconds between connection to the remote modem and sending the first poll message.  Used for line stabilization.  Default = 0.

Between-Call Delay

The time to wait in seconds between finishing one call and beginning another.  Default = 0.

Hangup Delay. 0 (Default)

The amount of time in seconds after the last poll message before the hang up command is issued.  Default = 0.