Connecting the Video Turnstile Logger to the PC via RS485
An RS485 plug has 9-pins. It will be clearly labelled on the frame-based Logger and on the back panel of a boxed Logger.
RS485 is suitable when the Logger is far from the computer and when several boxes or frames are on one cable. You will have an RS485 output kit which includes an RS232-RS485 converter (a Microlink 800 adaptor) for connection to a PC.
This page:
- tells you how to connect the RS485 lead
- gives tips on making your connections
- tells you how to use the software to set up RS484 communications.
- gives pin-out connections
Connecting the RS485 Lead
- With RS485, you need to use a Microlink 800 adaptor to connect to the computer's COM (RS232) port. Plug the Microlink 800 adaptor into the PC's COM port.
- Connect the RS485 cable to the Logger and the Microlink 800 adaptor.
- You would usually use the 12 V DC plug-top adaptor supplied to power the Microlink 800 adaptor. In some situations, if you have a local LVT unit, you can use power from its power supply as follows.
Note: Only connect 12 V DC wires from one logging unit. All other sections of the RS485 should have 5 wire connections.Logger 9-Pin Plug ML800 Adaptor 5 (0 V) 6 9 (+12 V) 7
Tips on Making your RS485 Connections
- Try to arrange a local RS485 connection from your PC. Bring the LVT modules one-by-one to this local connection.
- Use VT Setup to change the address of each LVT module in turn (Section 3.6 of the Video Turnstile User Manual). LVT modules are sent out with default address 0. If you connect the LVT to your RS485 link, and power up the LVT, VT Setup should find it at address 0. You will need each LVT on an RS485 connection to have a different address. Start from 1 and work up. It is best to leave address 0 free so that you can add a new LVT to your system and find it while all the others remain connected.
- If you do not arrange a local connection, check each LVT in turn.
That is, go to the nearest LVT to the PC with only a single section of
cable between the PC and LVT, and disconnect the rest of the LVTs.
Check the continuity of the cable by twisting the Tx+ and Tx–, and the Rx+ and Rx– wires at one end of the cable section and using a multimeter to check continuity at the other. (See the Pin-Outs below.)
You can then check continuity of a new length of RS485 cable and attach it to the 5-way screw terminal block. - RS485 cable should be 2 twisted pairs + screen. Use:
1 pair for Tx pair
1 pair for Rx pair
and screen for signal ground.
Telling the Software about your RS485 Links
- Make sure your Video Turnstile units are switched on.
- From the Windows Start menu, choose the Windmill 6.0 program group then select VT Setup.
- Choose the Unit Select tab.
- Select RS232/485 or Modem.
- Enter the number of the COM port to which the LVT is connected.
- Click the Connect button. This closes any existing communications link and opens a new one using the port specified.
You are now ready to use the VT Setup software to create a site.
RS485 9-Way D Plug Pin Out on Logger
The pin-connections of the RS485 plug on the Logger are as follows
1 Transmit-
2 Receive+
3 Receive-
4
5 0V
6 Transmit+
7
8
9 +12V
RS485 Logger to Microlink 800 Adaptor
| Logger 9-Pin Plug | ML800 Adaptor |
| 6 | 1 |
| 1 | 2 |
| 2 | 3 |
| 3 | 4 |
| 5 | 5 |
Note: When the flat side of the adaptor is on top, and the "curly" side underneath, pin 0 is to the left and pin 7 to the right.