Condition:New
Type:Logic ICs
Product Overview: DAM-DS1808 is a digital temperature acquisition module, supports 8 DS18B20 digital temperature sensors, and has 2 relays, which can be used for high / low temperature alarm output.
Application fields:
◆ Industrial temperature measurement
◆ Environmental monitoring
◆ Intelligent Instrumentation
Module features: ■ Support American DALLAS 1-wire bus digital temperature sensor;
■ Temperature measurement channel: 8 channels;
■ Temperature measurement range: -55 ～ + 125 ℃;
■ Temperature measurement distance ≤100m (cable requirements: distributed capacitance <100pf / m, it is recommended to use shielded twisted pair);
■ Support RS485 communication interface;
■ Supports standard Modbus-RTU / ASCII;
■ Baud rate support 1200/2400/4800/9600/19200/38400/57600/115200;
■ Communication distance: <1000 meters;
■ Provide configuration software, which can configure 485 address, communication baud rate, and information playback mode;
■ Support 2 relay outputs (high / low temperature alarm / independent control);
Physical map: 
Five, wiring 1.DS18B20 wiring method
VDD --------- VCC of DS18B20
DQn * --------- Signal of DS18B20
GND --------- GND of DS18B20
Note: “n” means the nth data.
2.RS485 connection
485A + -------- A +
485B- -------- B +
Original temperature value conversion temperature algorithm: The original temperature value OrgVal & 0x800> 0 (the 12th bit is 1), the collected temperature is negative:
Temperature value = (((the original temperature value read by the channel & 0xFFF) ^ 0xFFF) +1) *-0.0625
The original temperature value OrgVal & 0x800 == 0 (the 12th bit is 0), and the collected temperature is positive:
Temperature value = (original temperature value read by the channel & 0x7FF) * 0.0625
Example 1:
Sampling to a raw temperature value of OrgVal = 145 (HEX)
OrgVal & 0x800 == 0, temperature value = (OrgVal & 0x7FF) * 0.625
= 325 * 0.0625
= 20.3125 degrees
Example 2:
Sampling to raw temperature value OrgVal = CD0 (HEX)
OrgVal & 0x800 == 0, temperature value = (((OrgVal0xFFF) ^ 0xFFF) +1) * 0.625
= (32F (HEX) +1) * 0.0625
= 816 * 0.0625
= 51.0 degrees
