AMS 4081 user manual unit ID dip switches

4081 User Manual Issue 2

(these subsequent units should have the blue USB/RS485 button on the rear pushed out to select RS485 control).

The RS 485 communication protocol uses standard RJ9 connectors for connecting cables where multiple units can be chained together (cabling not supplied).

Please note that when connecting multiple units, each 4081 should have a unique ID as described below.

Cable Specification

The RS-422 specification recommends 24AWG twisted pair cable with a shunt capacitance of 16 pF per foot and 100 ohm characteristic impedance.

These recommendations should be used for RS-485 systems as well.

We also recommend using shielded cable.

There are many cables available meeting the recommendations of RS-485 made specifically for this application. Another choice is the same cable commonly used in the twisted pair Ethernet cabling. This cable, commonly referred to as Category 5 cable, is defined by the EIA/TIA/ANSI 568 specification.

This cable has a maximum capacitance of 17 pF/ft (14.5 pF typical) and characteristic impedance of 100 ohms.

Category 5 cable is available as shielded twisted pair (STP) as well as unshielded twisted pair (UTP) and generally exceeds the recommendations for RS-422 making it an excellent choice for RS-422 and RS-485 systems.

4081 unit ID dip switches

When remotely controlling more than one unit, the ID dip-switches on the rear of the unit need to be set so that each sequentially numbered unit on the chain responds to the correct commands.

The first 3 switches from left to right are used to set the machine IDs from 1-8. These switches are On when in the down position (the right-most switch on this block – Switch 4 - puts the unit into 'Bootloader Mode' where the unit software can be updated via USB, so is therefore not used to set the unit ID).

Unit ID	Switch 1	Switch 2	Switch 3
1	Off	Off	Off
2	On	Off	Off
3	Off	On	Off
4	On	On	Off
5	Off	Off	On
6	On	Off	On
7	Off	On	On
8	On	On	On

Where there are more than 8 units on an RS 485 chain, the IDs for units greater than 8 are set using a dip-switch on the switch-block labelled SW2 inside the unit (just next to a programming connector labelled J14 on the middle left of the board).

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