Ten Proven Rs485 Cable Methods > 자유게시판

On the other hand, the secondary serial port (Serial2) is implemented using hardware pins PA3 (input) and PA4 (output), and is controlled by the associated interrupts IC4/OC5 and OC4, respectively. For those of you interested in the details, here’s how it works: The low-level serial driver routines named Key(), AskKey() and Emit() are revectorable routines that can be redirected to use either of the serial ports. To use a QScreen as a slave in a multi-drop network, simply define a word, (named Silence(void), for example) that when executed calls RS485Receive() to wait for any pending character transmission to complete, then disable the transmitter, and then execute a routine such as Key() to listen to the communications on the serial bus. RJ11 jacks support half-duplex or full-duplex communications. These cables allow the dual RJ11 jacks of the RS485 option board of Laureate meters (digital interface ordering option 2) to be daisy chained and to be addressed digitally with no need for a hub. This cable provides a USB type A connector for the PC end and an RJ11 connector for the meter end. At the end of a received character, the service routine takes about 45 µs.

Extending a RS232 line is done by converting the RS232 signal into RS422 and then back to RS232 at the remote end. 5 should work in your situation because of the voltage you will be running (5-10V) and your signal is not high frequency (above 500Mhz) in the first place. The data COM port on the base of the Solis inverter uses a small round 4-pin plug with a screw thread to hold it in place when connected. RS485Receive() clears bit PD5 to place the transceiver in receive mode, and RS485Transmit() sets bit PD5 to place the transceiver in transmit mode. The QScreen Controller controls the RS485 transceiver with bit 5 of Port D of the processor. Ltd., which supplied the necessary equipment to communicate with the visualization application controls and heat meters, mounted on each node. If your application requires use of the secondary serial port as well as other interrupt routines, the key is to keep the interrupt service routines short and fast. Thus, as a rough approximation, operating at 4800 baud full duplex requires about 40 to 50% of the 6811's CPU time (that is, an average of approximately 40 to 50 µs service time every 100 µs).

In most cases the times are less than 25 µs which does not pose a problem. Access control systems: Rs485 cables are mainly used to connect and transmit data between access control devices such as security gates, RFID cards, or time attendance machines and the control center. It may be used to control video surveillance systems or to interconnect security control panels and devices such as access control card readers. Plus a lot of times the data rates are so slow on these bar code readers because they're only sending a few kilobits. What communication protocols are supported by RS485? You can use the QScreen’s RS485 link to create such a multi-drop serial network. In these distributed processing networks, a variety of machines and instruments work locally, but communicate and share data or resources with one another globally using a single serial link. We recommend that you keep the faster Serial1 port as the default serial link as you work through the exercises in this book.

If you have not yet compiled the GETSTART program and you want to do the exercises here, open GETSTART.C in your TextPad editor, click on the Make Tool, and after the compilation is done, enter Mosaic Terminal by clicking on the terminal icon and use the "Send File" menu item to send GETSTART.DLF to the QScreen Controller. We’ll use code from the GETSTART.C program. In fact, the program works the same as it did before, but now it is using the secondary serial port instead of the primary port -- and you didn’t even have to recompile the code! C program’s source code file. The two values provide a sufficient margin for a reliable data transmission even under severe signal degradation across the cable and connectors. To ensure that no two devices drive the network at the same time, it is necessary that each slave device be able to disable it’s own RS-485 data transmitter. If you ever wanted to connect to device in the same building (e.g. to machinery on production hal) and to you have to go to it to connect your computer.

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