GPRS modem configuration sections

As shown in Figure 15, the GPRS Modem Configuration view has the following configuration sections:

In addition, GPRS Status and Runtime Data tabs near the bottom of the view shows data served up from modem.

Modem Configuration

This section of the platform GPRS Modem Configuration view includes the following properties:

Enable GPRS Modem

(Checkbox) Must be set (checked) to enable the modem. Note changing from disabled to enabled requires a JACE reboot to become effective.
Local (not over the air) Baud Rate

With drop-down menu selections from 460800 baud to 9600 baud. This is the baud rate at which the JACE comm port talks to the GPRS modem. It is not representative of the actual data throughput of the GPRS modem, that is, this is not the “over the air” baud rate. Note that:
- Takes effect only after a reboot.
- Defaults to 115200 baud, which matches factory default rate of the GPRS modem. In general, the fastest rate supported by the modem is best.
Debug Level

To specify how much information is sent to the serial shell console output (the JACE’s “system shell” jumper must be installed), with choices trace, message (default), warning, error. Any change takes effect immediately.
Enable Poll for Monitor Data

This allows the monitor thread to poll the modem’s second port (ASC1) independently of any traffic (that is, PPP) on the primary modem port (ASC0). Data polled includes items in the “Monitor Data” section of the bottom-most runtime data area of this view. Any change takes effect immediately.
Monitor polling data includes signal strength, which is used to flash the “Signal LED” on the GPRS modem option card. Therefore, if this property is disabled (cleared), the Signal LED will flash a 1 sec. On / 1 sec. Off pattern to indicate the signal level is not being read.
Monitor Data Poll Cycle Time

Specifies how often the low-level modem driver polls for data in the “Monitor Data” section of the bottom-most runtime data area. Any change takes effect upon timeout of the previous monitor.
Max Time Scripts Can Fail Before Modem Reset

Specifies the duration that “modem quite time exceeded” from scripts (monitor thread) failure can occur before a modem restart is attempted using the AT^SMSO shutdown command. Range is from 5min. (default) to any greater time.

Provider Configuration

This section of the GPRS Modem Configuration view is to specify the cellular provider (corresponding to the SIM card installed in the GPRS modem option), along with numerous properties related to the PPP (point-to-point) protocol used for GPRS connections.

Provider configuration properties include:

Unless noted otherwise, changes to these (checkbox) properties become effective as follows:

If changed while a PPP session is not already active, the change is effective immediately (and a PPP session is attempted immediately).
If changed while a PPP session is already active, it takes effect on the next PPP session (current PPP session must end first). The current PPP session normally ends on “Max PPP Idle Time Before Disconnect”.

Allow PPP Connections

(Checkbox) Typically you leave this set (checked). If a PPP session is active, clearing this will force the PPP session to end. If a PPP session is not active, and this is cleared, another PPP session will not be attempted.

The typical use case for leaving this cleared is when you want to have SMS messaging available, but don’t care about PPP. Or, for some reason (perhaps during initial startup) you don’t want to be sending data through the provider’s network—say, you don’t have a “front end” set up yet.
Do not clear (uncheck) this unless you have some other local (alternate) connectivity to the JACE, otherwise, you will be unable to regain access.
Enable On-Demand PPP

(Checkbox) Determines how and when the PPP protocol stack is initialized by the driver software.
- If disabled (cleared), then an attempt to start the PPP stack is performed shortly after JACE boot. Consider this the “always on” usage of PPP. The items “Min time before reconnecting PPP” and “Max PPP Idle Time before disconnecting PPP” both come into play in this mode.
- If enabled (checked), then the PPP stack is initialized only “on demand” whenever the IP stack requires communications, and a route does not already exist to the destination. Consider this the “autoconnect” mode of operation. The property “Max PPP Idle Time before disconnecting PPP” is used, but the property “Min time before reconnecting PPP” is ignored in this mode.
Enable PPP Debug

(Checkbox) Enables the PPP stack to send detailed information to the serial console of the JACE. This can be useful to troubleshoot when PPP parameter negotiation or authentication fails.
Switch Gateway on PPP Connection

(Checkbox) After successful initialization and connection of the PPP stack, typically the PPP server will have assigned a gateway address to use for the IP stack. If enabled, this property will cause the original gateway configured in the JACE’s TCP/IP configuration to be temporarily “swapped out” with the gateway assigned during the PPP client/server negotiation. This allows connectivity to IP addresses that are on the PPP subnet.
Provider APN

The Access Point Name for the cellular provider network. The APN specifies the gateway between the mobile network and the Internet.
APN User Name

User name used to authenticate to the provider network.
APN Password

Password used to authenticate to the provider network.
PPP Authentication Type

Used to set the authentication type for the PPP session, where choices are:
- none
  
  No authentication
- PAP
  
  (Password Authentication Protocol), where in most cases, either this or CHAP is acceptable.
- CHAP
  
  (Challenge Authentication Handshake Protocol), where in most cases this or PAP is acceptable.
- MS-CHAP-V1, CHAP, PAP
  
  (some combination of Microsoft’s version 1 of CHAP, CHAP, or PAP).
Min Time Before PPP Reconnect

This specifies a timer timeout that is enforced whenever a PPP session terminates for any reason. This is the time that the PPP stack will remain deactivated before any attempt to restart can be initiated.
Max PPP Idle Time Before Disconnect

Once the PPP session has been started, inactivity on the link for this amount of time will cause the PPP session to terminate. Default value is 30 minutes.
Max PPP Active Time Before Disconnect

(Available in AX-3.6, also builds 3.5.30 or 3.4.61 or higher) If set to 0 minutes (default if upgraded from previous 3.5 or 3.6 build), this timer is disabled. If a new modem under AX-3.6, the default is 1 day (24h 00m). This setting is available for the use case where the “Max PPP Idle Time Before Disconnect” has been set to 0 (disabling idle timeout), or if it has been set to some number; however, the occasional data sent by the station expects no response.

In either of the above scenarios, if an abrupt service outage from the network provide occurs, it is possible that pppd or the GPRS modem may never be notified that the PPP “pipe” it is using is no longer valid. The result is the JACE becomes unreachable from the remote end.

By specifying a time in this property, a shutdown and restart of PPP occurs even if the link is not idle, or if the idle time is disabled. Typically you should set this to a time much larger than the “Max PPP Idle Time Before Disconnect”, but one that would allow guaranteed “refreshing” of the link.
Max Number of Times LCP Can Fail Before Modem Reset

Specifies the number of unsuccessful LCP (Link Control Protocol) requests by the pppd before the the AT^SMSO command is sent to reset the modem. Default value is 10, range is from 2 to 100.

SMS Configuration

This section of the GPRS Modem Configuration view defines the behavior of the SMS (Short Message Service) handling portion of the GPRS modem driver. Properties include:

SMS Service Center (may be blank)

Specifies the phone number of the SMS service center. Depending on provider, this may be preset in the SIM card in the GPRS modem, and so may be blank. Any change takes effect immediately.
Auto delete messages after reading

If enabled (checked), messages marked as “REC_READ” are deleted. Messages are marked “REC_READ” if they are read by external agents (such as the SMS platform service). Also, if the SMS message is marked as “REC_UNREAD” and it is a special “remote command” type of message, it is also deleted, regardless of this setting.
Enable remote SMS commands

If enabled (checked), this allows the processing of special SMS “commands” that were sent remotely. See Remote SMS commands.