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TRS3232: Communication failure with TRS3232

Part Number: TRS3232
Other Parts Discussed in Thread: MAX3222E
We have used 3.3V operated IC TRS3232IPWR for RS232 communication , below are the design details and issue what we are facing :
  • IC TRS3232IPWR is used in Device 1 and Device 2 RS232 port
  • Y cable is used to communicate from PC to Device 2 and Device 1 to Device 2
Issue faced :
  • Communication failure between PC and Device 2 : When PC start transmit, signal supposed to be received at Modem' IC Rx and also at the Meter' IC Tx pins and due to this communication failure occurs. Here we can see that transmit signal from PC end and Meter' IC Tx pins are collide with each other such that valid signal does not receive at Modem IC Rx pin.
Observations: 
  • When PC connection fails with Device 2 , the voltage level of RS232 signal (PC TX) is from -5.6 to 1V, no valid signal received at Modem IC Rx pin
  • Here when I change the IC at Device 1 from TRS3232IPWR to TRS232EIDR (5V supply) then communication establish successfully with valid signal levels : -5.6 to +5.6V and Modem responds with same voltage level
  • During communication, 3.3V supply to IC TRS3232 is Ok, no drop observed in supply 
Query :
  • Please suggest possible reasons of communication failure with IC TRS3232IPWR