Technical Application Note

Conﬁguring the 615M-1 serial client and serial server

Purpose

This application note demonstrates how to configure

the ELPRO 615M-1 Wireless Modem as a serial client

and serial server for a point-to-point RS-232 connection.

The 615M-1 supports an RS-232 serial client and serial

server for point-to-point communication, and allows for

point-to-multipoint serial communication for up to 50 devices

when used with the ELPRO 605M-R1 Cellular Serial Router.

ote:N This application note covers point-to-point connection

without the use of a 605M-R1 router. It does

not describe how to provision the cellular PPP

connection. For instructions on configuring that

connection, see the 615M-1 quick start guide.

Network example overview

The following illustration shows a typical serial client

and serial server connection between two 615M-1

cellular modems. All cellular connections must be fixed

cellular (PPP)IPaddresses, and can be either public or

private. When using fixed private cellular SIM cards,

you need to select the “Modem-to-Modem” option on

the Cell Connection/Carrier page of the 615M-1 Web

interface to enable point-to-point and point-to-multipoint

communications.

A serial client establishes a connection to the

serial server on a defined port. A serial server

never establishes a connection; it can only accept

a connection. With this in mind, the serial server

typically needs to be located at a central location

if the configuration requires more than one serial

client device.

Conﬁguring the 615M-1 serial server

Use the following procedure to configure the

centrally located 615M-1 as the serial server.

1. Log onto the Web interface of the 615M-1 to be

configured as the serial server.

2. On the menu, click Serial.

3. For the Electrical Interface setting, select

RS-232.

4. Set the baud rate, data/stop bits, and parity to

suit your application.

The settings used in this example are 9600, 8,

1, N.

RS-232 cable

PC running

terminal software

PC running

terminal software

615M-1 Cellular

Modem and Router

615M-1 Cellular

Modem and Router

RS-232 cable

Cellular

network

Serial Client and Serial Server Connection Between Two 615M-1 Cellular Modems

Technical Application Note September 2014 www.eaton.com

5. Leave the DTR setting at the default, AT&D0.

This setting ignores the DTR. The DTR control is used

by the client to establish a connection to the server.

Because this modem is selected as a server, DTR can

be left at the default setting, which ignores the DTR.

6. Under the External PAD Settings, select Server as the

PAD Mode, and select TCP as the PAD Protocol.

7. In the Incoming Friendly IP Address field, enter the

cellular IP address of the remote modem (the serial

client).

You can find the cellular IP address of the remote

modem by logging onto its Web interface and

displaying the Unit Status page.

8. In the Incoming Port field, enter the TCP port to be

used.

Both the serial server and serial client must use the

same TCP port. Port 5002 is used in this example.

9. Click Save.

Serial Server Configuration

Conﬁguring the 615M-1 serial client

Use this procedure to configure the remote 615M-1 modem

as the serial client that will establish the connection to the

serial server.

1. Log onto the Web interface of the remote 615M-1

modem.

2. On the menu, click Serial.

3. For the Electrical Interface setting, select RS-232.

4. Set the baud rate, data/stop bits, and parity to suit your

application.

The settings used in this example are 9600, 8, 1, N.

5. Set the DTE as follows:

This application example demonstrates two PCs

connecting their terminal sessions together. There are

two types of serial communication devices, DTE and

DCE. PCs are DTE devices, which means by default the

DTR line (pin 4) is ON.

• For DTE devices, select AT&D9 from the DTR

drop-down menu. The modem connects to the

server when DTR is ON. When DTR is OFF, the

modem does not connect or the connection will

close if in session.

• For DCE devices, such as other modems or ELPRO

115S modules, DTR is OFF by default. For these

devices, select AT&D8 from the DTR drop-down

menu. The modem connects when DTR is OFF and

disconnects when DTR is ON.

For more information, see the Help link on the Serial

Web page.

6. Under External PAD Settings, select Client as the PAD

Mode, and select TCP as the PAD Protocol.

7. In the Outgoing Port field, set the outgoing port to

match the incoming port of the serial server.

Both the serial server and serial client must use the

same TCP port. Port 5002 is used in this example.

8. In the Remote Host IP Address field, enter the cellular

IP address of the serial server.

You can find cellular IP address of the serial server by

logging on to its Web interface and displaying the Unit

Status page.

9. For TCP Client Keep Alive, select the Enabled option.

When this option is enabled, an “alive” packet is

periodically sent from the client to the server in order to

detect a broken connection. The modem automatically

tries to re-establish the connection if necessary.

10. Click Save.