Need Help Reading Keyence Sensor

I am trying to hook up a Keyence Laser Displacement sensor to my Arduino for displaying on an LCD readout. The Keyence unit has an RS232 (9600,N,8,1) connection which communicates the laser sensors distance. If I connect this directly to my MAC (using Coolterm) I am able to receive the distance data. If I connect the Keyence to my TTL/RS232 Adapter to my Arduino, the Arduino does not receive anything.

Trouble shooting steps I have already taken:

-I've connected the MAC/RS232 directly to the MAX232/Arduino and can get bidirectional communication no problem.

-I've looped the CTS/RTS and DCD/DSR outputs on the Keyence RS232 connector so the only wires going to the Arduino are Transmit, Receive, and ground.

-I've tried 2 different manufacturers of TTL-RS232

During troubleshooting I had it working for a fraction of a second when I had both the Arduino and MAC connected to the Keyence using a DB9 loop-through breakout adapter. I know RS232 is Pt to PT and this was not a great idea, but I was desperate for a solution. Everything so far has me feeling like the Keyence is looking for some voltage/signal it isn't getting from the TTL-RS232 adapter, but I am not experienced enough with RS232 to know what that is and what I am doing wrong.

Any help would be greatly appreciated - please let me know if I am leaving anything out.

Check the TX and RX lines on both units. Make sure you connect an input to an output.
On some devices a TX line can be an input on others an output, it depends on how the device is classed.
Start of with TX and RX unconnected. Use a scope or LEDs to see that your TX produces flashing, if not try the RX. On the arduino the RX is an input and TX an output. It might not be the same on your adapter.

Over the past few days I've checked all the TX and RX lines multiple times - or so I thought. The one I did not check was the physical DB9 connector on the RS232/TTL adapter which turned out to be the problem. The pinouts did not pair up properly with the Keyence unit. I made a little DB9 M-F cable that reversed pins 1-5 and voila!

Thanks for your Reply Mike - greatly appreciated!

I too am a complete newbie. Would you be able to post sample code that you used to read in from the serial line so I can get my Keyence up and running. I have the exact same hardware as you and potentially the same issue with the correct Rx Tx configuration.