How to connect four SRF 04 ultrasonic sensor with single Arduino Board

I am interfacing four SRF 04 ultrasonic sensor with a single Arduino UNO board. But I am getting only single reading from the first one (as mentioned in the code). I have used also a external signal spliter circuit with external power supply. But no result. Only one SRF 04 is active.

Do anyone have any idea??? Please help me.

Thanks & regards,

Dip N Ray

Are each of the sensors connected to a different pin?

No. I have used one trigger PIN to connect two SRF 04 using a TTL signal splitter circuit. 5V power and ground are supplied from external source. Echo outputs from SRF 04s are received at different PINs. Actually I am using four SRF04s, one Compass, XBee communication (TX & RX) and H-bridge for my work and I need 16 pins fron Arduino Uno. So I have used the same trigger pulse for the SRF 04s. How is it possible?

If you try triggering them all at once, you will have problems with interference. To use more than one of those sensors, you need to trigger them, one after the other, at different times. And don't trigger the next one until the echoes from the previous one have been detected.

OK. Thank you very much for your reply. I will do as directed and let you know.