DIN rail modules for automation and remote control

Overdigit produces programmable PLCs and expansion I/O Modbus modules. The common features of all modules are:

• Interconnection of the modules via RS485 bus
• 24Vdc power supply with low power consumption
• Connections using removable screw terminals
• 113mm height, 119mm depth, 17.5 / 22.5mm width
• Protection rating: IP20
• Operative temperature: -20°C ÷ 70°

All modules, PLCs and I/O expansions, are interconnected by RS485 serial bus and these can also be used with any other commercial device with Modbus protocol. However, between Overdigit products, it can be obtained communication performance up to 10 times faster than the fastest Modbus systems on the market. This thanks to the communication speed which can reach up to 1Mbit/s and to the special functions integrated into the CoDeSys development tool. By placing the modules in the “PLC configuration” of the tool, all the I/O resources are automatically updated with a single exchange of frames between the master PLC and a slave module. Normally the Modbus systems require the execution of several successive commands to get the reading and writing of all I/O. With Overdigit systems this happens with a single command and this also reduces the protocol overhead time.

PLC with high number of I/O in narrow spaces

The Overdigit modules have the characteristic of extreme compactness. The PLC modules use 22.5mm of DIN rail and expansion modules take only 17.5mm while having a high number of I/O compared to the competition. For example, with only 110mm of space on the DIN rail, it can be possible to assemble a CoDeSys PLC with 80 digital inputs and 40 static outputs, 24V with current up to 2A and short circuit protection. Usually static outputs of similar products are made with simple low current optocouplers while Overdigit modules can directly drive higher loads without adding external relays.

All analog signals in one module

The EX08AI expansion slave module can claim technical features unique in the market. In one module, with 17.5mm width, are available 8 analog input channels, individually configurable for voltage, current, thermocouples, thermo-resistance, NTC, resistors and potentiometers. No more need to manage different models of analog interfaces but, with one configurable product, all needs of analog acquiring can be satisfied. In addition to the large variety of signals that can be connected directly to the module, it is necessary to highlight the presence of measurement scales that are difficult to find in competitive products, such as the scale for the measurement of voltages up to ± 50V. Additionally, all scales make use of high resolution converters that allow to obtain a stable and precise measurement of 20000 points on the scale 20mA or the resolution of the tenth of a degree on temperatures. Another important feature is that the 8 available channels remain anyway 8 independent channels also using three-wire sensors such as, for example, the Pt100 and Pt1000 thermo-resistance. Usually, in similar products, to compensate the resistance of the cable, the measurements are made using the terminals of the other channels, thus reducing the actual number of available signals.

CPU with integrated radio modem

The Web PLC is available in two versions, GPRS and HSPA, that integrate within them a radio modem GSM and UMTS respectively. This modem is handled by only one function block of CoDeSys library that performs all operations of Internet data access, SMS sending/receiving and phone calling with number identification. The above functions can be used simultaneously with the data connection thanks to the multi-port management of the modem. The Internet data connection also includes the DynDNS client to update, in the DNS server, the value of its dynamic IP assigned by the mobile network operator. The management of the SMS allows the sending and receiving of SMS with a maximum length of 1536 characters. Also provided are an indicator of the number of new available messages and SMS sending confirmation function. The function block can also call a particular phone number or receive commands using the caller identification and counting of rings. This function is very useful to instruct the PLC via simple telephone calls to the SIM number without any charge of cost.

The web at your fingertips with the HTTP client function

The Internet is an immense archive of resources of all kinds with which the Web PLC can interact, thanks to the advanced HTTP client function block available in the CoDeSys library. This block is used to send a request to a specific URL and get the relative resources from a server located on the Internet. Servers can contain pages, information and data, or they can perform particular tasks requested by the PLC and reply to it the result. The HTTP client function is also the basis of the communication with portals and databases for telemetry purposes and also of  the new and emerging technology called “Internet of Things”. The function block manages access to password-protected servers and also provides secure access to servers using SSL.

Sharing files with the FTP client function

The TCP/IP network library of the Web PLC includes the FTP client function block that offers further possibilities to the PLC to exchange data with the whole world. With this feature it is possible to log in to an FTP server and then use in sequence one or more specific commands. Commands are available for copying a file to and from the server, creating a folder and deleting files and folders. The FTP connection can be established also on secure servers through SSL management. The Web PLC is also equipped with an FTP server through which all hard drives are accessible (internal and external on SD card and USB memory stick).

E-mail and attached files with the SMTP client function

The SMTP function block of the Web PLC allows the sending of an E-mail to a specific address, attaching any type of file on the hard disk of the PLC. This function is very useful to send production reports or alarms simply by defining the fields Subject and Text of the E-mail. The attachment can instead allow the sending of a logging file previously created by the PLC. This client function also includes the management of SSL to access all servers that use secure connections as gmail.com.