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Showing results for tags 'scan_ex'.
Good evening ladies and gentlemen, I have 4- V430-J-TA24's, serial (RS232, 9600, 1, none) MODBUS, one as a master (MTU), and the other 3 as slaves (RTU). port 1 on each unit connects to it's respective radio modem. The MTU polls the 3 RTU's successfully and the cycle repeats. Here is my problem: how do I detect a comm failure on the slaves that will set a MB to clear my outputs and registers? The master reads a register from RTU1, here it can use the status message from the RHR #3 and use a compare if MI96 (rhr#3 status) = D#5 then ----[R] (MI100, the value displayed on MTU, fetched from RTU). Now on to RTU 3 and 4, they only have a MODBUS config FB follow by a SCAN_EX. How does the RTU know if updates cease? The registers and coils will just hold their last set values. My thought is having the master toggle a MB on/off in the slave, then somehow implementing logic in the slave to detect if MB being stuck in a 0 or 1 state for greater than a defined amount of time. this would trigger a bit that would zero out the coils in the slave. Please someone tell me there is an easier way. Also what is the reason that RS232 port 1 (RJ11) seems to be disabled while connected to a PC with the USB cable? Thanks!