Contact Closure; Rs-485 Multi-Drop; Wiring Notes - Image Sensing Systems RTMS G4 User Manual

Chapter 2

Contact Closure

The G4 can provide, in parallel with the serial port and RF/IP/Cellular communications, up to
16 contact closures to deliver real time presence indication in each of its detection zones. The
contacts are arranged in two wiring configurations and operating modes:
•
8 Isolated contact pairs (as in RTMS Models X2/X3 and K3). In this configuration each of
the contacts is isolated from the other.
•
16 contact pairs. In this configuration all contacts will share a common Serial Ground. The
contact closures can be configured to operate either as Single Loop mode or Dual Loop
(Speed Trap) mode. Single mode provides up to 12 lanes or zones of detection, Dual mode
provides up to 8 lanes of Dual Loops
You should wire the cable based on your preferred contact closure output mode and set the
RTMS mode using the Contact Closure Setup in the Advanced screen of WinRTMS.

RS-485 Multi-Drop

The RS-485 setting of the G4 Serial Port allows up to 32 RTMS units to be employed on the
same serial bus for distances up to 4000 feet (1200m).
The diagram below shows the use of a 4-Wire line. The use of a half-duplex 2-Wire line is
feasible but it is suitable for data collection only. Consult RS-485/422 Application Guides for
details on wiring solutions for your project.

Wiring Notes

1. The DB9 connectors and terminal blocks serve as a disconnect point, which allows
disconnecting the RTMS from the transmission line for direct connection to the laptop's
COM port for setup.
2. Terminating resistors (100-120 ohms) are required at the extreme ends of the Receive and
Transmit transmission pairs.
3. Transmit and receive pairs must be transposed when connecting to a DTE (PC, Data
processing System). To interface with a PC an RS-485/232 converter may be required as
PCs typically do not have RS-485 interfaces.
4. RS-485/232 converter connector type and pin assignment are not shown as these are not
standardized and vary between models.
G4 User Manual
Figure 2.10. RS-485 Multi-Drop Wiring
RTMS G4 Installation
© 2009 ISS Canada 2-11