| ??? 11/21/05 00:25 Read: times |
#103932 - NOT dangerous if you read properly Responding to: ???'s previous message |
Erik Malund said:
RS232 in the following way .... then it can transmit 1 character when there is no activity on the RX,
a dangerous approach. This would require The 232 trqnsmitters to be short circuit proof and you would still have collisions. You do not know of "activity on the RX" till a character is complete (1ms at 9600). Even connecting Rxd to EI0 will fail occasionally albeit much more rarely. Erik Erik, Please read before jumping in. I have said that the RX pins on the micros are tied together and the TX pins are tied together and then there is ONLY ONE transmitter and ONLY ONE receiver on the RS232. I do not see what needs to be 'short circuit proofed'. Since the TX and RX pins on the micros are 'active low' they can be tied together because an 'AND' function is performed. As for what you call a dangerous approach: All slaves get the same message, so the master can send an 'end of message' marker and simple timing on the slaves will avoid any collisions. Regardless of your views, the system has been working very well for over a year. Tony |
