Dear ALL I want to help form your sit in following scenario. I have 5 89c51 one is master and other 4 are slave. Mater can communicate with PC through serial port and Master can be communicating with other 4 89c51.Basically I am using 4 slave for expansion of IO pins.I an not understanding that when Master communication with PC how is communication with slave because Tx and Rx is connected with MAX-232. Communication sanarios is some stream coming from PC Master Read the Stream and transmit a protocol to the slaves and slaves read the stream and targated slaves pick the information and send byte to his port . My question is when Master is communicating with PC how is communication with slaves Thanks.
"I an not understanding that when Master communication with PC how is communication with slave because Tx and Rx is connected with MAX-232." You need to use two separate serial ports on your "master" 8051 - one to communicate with the PC, and the other to communicate with the "Slave" 8051s. For the communications between the 8051s, look at the "multiprocessor" mode of the 8051 UART; see: http://www.keil.com/forum/docs/thread5457.asp
You need to use two separate serial ports on your "master" 8051 - one to communicate with the PC, and the other to communicate with the "Slave" 8051s. Not really, if they are on the same board (or in the same cage) there are many other means (IIC, SPI parallel ....) Erik
Ur right i have to implement two serial port one for PC and other for MCU. Master and PC communication is not a issue.Because its done by enabled Serial intrrup. How will communicating with slaves.its timer intruup driven or how?
"Ur right" Please don't do that! "i have to implement two serial port one for PC and other for MCU." As Erik pointed out, there are alternatives for the interprocessor comms. But, if you want to use an asynchronous (UART) serial link, then you will need a second UART. "How will communicating with slaves.its timer intruup driven or how?" Just choose a device with two UARTs - it will have a second serial interrupt for the second UART!
My problem is that i have to used 89c51 that have one URAT. That already engaged with PC. Have u any solution that can i communicate with slaves (Asyn or other method)
Have u any solution Since you are asking micro, why do you not send him an e-mail instead of using the forum. as Andy stated: "Ur right" Please don't do that! and you still proceed with the Stupid Monkey $#|+. Erik