Detcon DA-1 - Manual (Page 2)

Table of Contents
1.0 Description
2.0 Modbus Communications
3.0 Alarm Status per Channel
4.0 Diagnostics
5.0 Enclosure Assembly
6.0 Dimensions
7.0 Wiring Diagram
8.0 Warranty
1.0 Description
The Detcon Model DA-1 Data Acquisition Module is specifically designed for use where fire and gas sensor
devices are networked over an RS-485 communications loop using Modbus™ RTU protocol.
Although the Detcon Gas Sensors can be connected directly to the communications loop through their RS-
485 port, certain devices such as smoke and flame detectors provide either a dry contact or 4-20ma output.
The Detcon Model DA-1 Data Acquisition Module allows the customer to connect up to four of these
devices to the communications loop via its hard-wired inputs.
The DA-1 provides a combination of four analog or digital inputs and an RS-485 output. The DA-1 can be
provided with open contact supervision where it is configured for digital inputs. The RS-485 communication
protocol is the industry standard Modbus™ RTU. LED indicators on the front of the DA-1 indicate polling
status and whether there is an active alarm condition of any of the devices. The DA-1 is mounted in an
enclosure designed and approved for use in Class I; Div 1; Groups B, C, D environments.
2.0 Modbus™ Communications
The protocol used for the RS-485 communications is Modbus™ RTU. The information available to the host
controller includes the alarm status of any of the four channels. In addition, if the open contact supervision
capability is selected, a bit will be set in each channel’s fault register.
The network address of the DA-1 module (1-256) can be set via a bank of dip switches on the PC board.
Communications are set for 9600 baud 8bits no parity and 1 stop bit.
RS-485 addressing is in Hexidecimal format as shown below:
Detcon Model DA-1 PG.2