Modems; Example Setup - Siemens Milltronics BW500 Operating Instructions Manual

11.6

Modems

The BW500 and BW500/L has been successfully connected to several different modems. In
general, the Modbus protocol is a very modem friendly protocol. This section gives some general
guidelines on modems and their connection. For detailed information, see the modem
documentation.
Picking Modems
There are several different types of modems; dial-up, leased line, radio-link, fiber-optic, to name
the most common.
Dial-up
uses a standard analog phone line and dials the number of the receiving modem.
Lease line
come in either 2 or 4 wire types and use special phone lines that are 'leased' from your phone
company (or you) and do not require any dialing.
Radio-link
come in many different types, but all use radio frequencies for transmitting the information.
Fiber-optic
uses a fiber-optic line to connect the two modems.
Each type of modem and each model have various characteristics. Before purchasing the
modem contact the modem manufacturer and ask if they have had experience using the
modems with Modbus protocol with no flow control. If they have, ask them what settings were
required.
Setting up the Modems
Modems can be configured using software, dip switches, jumpers, or a combination.
Dip switches are normally located at the back of the modem, jumpers are normally located on
the motherboard and require that you remove the cover. Software normally requires you to use a
standard terminal program and to connect to the RS-232 port on the modem and send special
commands. The most popular command set is called the AT, or Hayse, command set.
Your modem manual should give details on how to configure it.
11.6.1

Example Setup

For a typical dial-up modem, try the following setup as a first attempt:
BW500 and BW500/L
Operating Instructions, 12/2016, A5E33482052-AD
Communications
11.6 Modems
147