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AD to CT Modbus Hookup Page 1


First let's look at the pinout of the 15 pin AD communication port.
  1. 5V Power (+) Connection
  2. TXD Transmit data (RS-232C)
  3. RXD Receive data (RS-232C)
  4. RTS Ready To Send
  5. CTS Clear To Send
  6. RXD Receive data (-) (RS-422/485)
  7. 0V Power (-) connection (GND)
  8. 0V Power (-) connection (GND)
  9. TXD+ Transmit data (+) (RS-422/485)
  10. TXD- Transmit data (-) (RS-422/485)
  11. RTS+ Ready to send (+) (RS-422/485)
  12. RTS- Ready to send (-) (RS-422/485)
  13. RXD Receive data (+) (RS-422/485)
  14. CTS+ Clear to send (+) (RS-422/485)
  15. CTS- Clear to send (-) (RS-422/485)

We see the RS-232 signals (TXD, RXD RTS and CTS) and their RS-422/485 versions with (+) and (-) lines for each. RS-485 connections are formed for the Transmit and Receive lines by hooking the (+) leads together and the (-) leads together giving RXTX+ and RXTX-. Even though the handshake signals (RTS and CTS) are not used they still must be completed by looping back.

Do you really want to hook up to that at the 15 pin connector? If you aren't good with a soldering iron then forget it. Fortunately AD makes a nice DIN rail adapter (DN-15TB) connected by a cable (ZL-15DNTB-CBL)

Now let's look at the Control Techniques side
  1. Not Connected
  2. RXTX
  3. 0V
  4. +28V Supply (100mA)
  5. Not Connected
  6. TXEN\
  7. RXTX\
  8. Not Connected

We will only be using pins 2 (RXTX plus), 3 (0V or neutral) and 7 (RXTX minus) There are no RTS and CTS lines on this end to worry about. To make this connection you will also need some SHIELDED Ethernet cable with SHIELDED RJ-45 connectors. If you get the cable long enough you can cut it into two for two drives. (More about multiple drives later)

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The communication wiring





Copyright © 2005, 2006, 2007 Bernard Carlton
berniec@theplcguy.com