19
B
A
0V DC
B
A
0V DC
Screen
B
A
0V DC
RS485 Modbus
Comms Port
RS485 Modbus
Comms Port
RS485 Modbus
Comms Port
Interfacing to the Remote Modbus Port
Cable Sizing
Tocsin 650/750 Controller (slave)
Tocsin 650/750 Controller (slave)
Master DCS/BMS
Note only the A,B and 0V DC Connections are
Used. 0V DC between master and slave should
be connected for correct operation and to prevent
damage to both master and slave systems
The Tocsin 750 series controllers have an in-built memory map allowing access to alarm status, panel
status, readings etc using Modbus RTU protocol. Wiring between units is as follows:
Refer to users guide for Modbus channel mapping
More than one controller can be interfaced on the same Modbus cable by
assigning individual Modbus addresses to each controller.
2
Up to 400m use minimum 1.0mm cable with an overall cable screen.
2
Cable runs over 400m use 1.5mm cable with an overall screen
Modbus
Address
100
Modbus
Address
99
Fit terminating
resistor at last
device across
A-B 120 Ohms
Summary of Contents for 2-Wire Systems
Page 4: ...3 SECTION 1 MOUNTING DETAILS FOR EQUIPMENT...
Page 9: ...8 SECTION 2 SITING GAS DETECTORS...
Page 16: ...15 SECTION 3 GENERAL CABLING PRINCIPLES CABLE TYPES AND CABLE SIZING...
Page 23: ...22 SECTION 4 MAKING DEVICE CONNECTIONS TO DETECTOR NODES...
Page 35: ...34 SECTION 4 Control Panel Interfaces and Connections...
Page 51: ...50 Notes...