plain ethernode^®:
ETH-A7-2SER

ethernode^® is available in the versions with LCD and without LCD and in many different I/O versions. The two serial interfaces that are described here are the minimal configuration of the whole ELZET80 Ethernet hardware.

Serial interfaces are often the easiest way to interlace units which do not have an own Ethernet access into the network.

For the connection of a remote device there is the possibility to simulate a serial interface at the local computer (Virtual COM-Port) or to program on the ethernode^® in order to preprocess the data (Web-Server or IP-Socket).

Virtual COM-Port

If only one user has to access over a longer distance, the fastest solution is mostly to work with virtual COM-interfaces. There a serial interface is simulated by ethernode as a local interface in one Windows computer in the network. The interface appears in Windows as COM4 or similar and it is available from every program. You find the details in "virtual COM-Port". The software switching between RS232 and RS485 by Windows is currently (July 2007) in the works.

Local programming

If e.g. an analyser or a scale have to be interlaced so that a data preprocessing occurs or so that several users can access in parallel, you have to use local programming on ethernode. In comparison to other RS232 converters ethernode satisfies here very well because mCAT firmware offers comfortable support for such a small unit: Over the webserver you can display e.g. the current values and statistic data and you can control the unit's functions also over the input fields an buttons. The coupling to your mCAT-C task can be processed by "mSP" or by special CGI instructions (see Webserver).

Socket Interface

Since a web interface usually requires users interaction, a TCP/IP communication is suited better, if data shall be transfered automatically. Therefor you would program a task on ethernode as "Server" which keeps data ready and converts it espectively for different "Clients", mostly Windows computers. If you have a scale that is connected to a RS232 such a server task would recall the scale's value regularly over the RS232 and hold respectively the current value ready for interrogating clients. Other functions would convert requests for taring et cetera. Details about Socket Interface here.

mCAT and the serial driver SerDrv

If you want to program this function the one-time buy of the mCAT application development system is necessary. Service programs to generate and download tasks and webstructures, the GNU C compiler for the ARM, a terminal program et cetera are part of it. In addition much documentation about programming and the service programs as for example SerDrv are included. SerDrv is a message interface to the serial ports of ethernode (or TSM-ARMCPU et cetera) and it can be parameterised so that for example signs that come from the interface are collected as long as finally an end sequence (e.g. a CRLF) is found. After that the collected signs are transfered as a message to the executing task. You send the message send-site to SerDrv which sends the signs afterwards over the serial interface in the backround interrupt.

Electrician-friendly

For the both serial interfaces two M12 cable connections are available. The cables are connected to the clamps at the right top. The first serial interface (SERO) only has the both datacables RxD and TxD as well as Masse (Gnd), the second serial interface (SER1) has furthermore also the handshaking signals RTS and CTS. If SER1 is programmed on RS485 (service program), then the clamps A/B (at RS232: RxD1/CTS1) build the halfduplex datapair and the fullduplex sending pair respectively, while Y/Z (at RS232: TxD1/RTS1) build the halfdupley RTS pair and the fullduplex receiving pair respectively.

Both serial interfaces can be set onto baud rates between 1200 and 115200 bis/s. Parity and stop bits are selectable, too. Usually you have access to the mCAT monitor Sysmon over SERO. If you want to use SERO for periphery, too, you can achieve this by modification of the EEPROM value. Then the monitor is only available over Ethernet. SERO has got no handshake signals, whereas SER1 supports RTS/CTS (as well as SerDrv). AT RS485 the two handshake signals build the second cable of the differential input respectively.