Contents
VM3209K New Hardware Manual Version V1.1
Hardware parameters
Specification
| Processor | 32-bit low-power processor |
| Frequency | 580Mhz |
| Power consumption | 4W |
| Operating temperature | -20~70°C |
| Storage temperature | -30 ~85°C |
| Working humidity | 5 – 95%RH |
| Certification | FCC/CE |
Network parameters
| Interface speed | 10/100M Auto |
| Electrical isolation | 2KV |
| Network Protocol | IP/TCP/UDP/DHCP/DHCPD/DNS/HTTP/SNMP |
| Maximum number of connections | 4096 |
RS485 Parameters
| Number of ports | 1 |
| Baud rate | 300~230400BPS |
| Data bits | 5/6/7/8 Bits |
| Stop bit | 1/2 Bits |
| Check | None/Odd/Event |
| Buffer | 4MBytes |
| Interface | Terminal(A,B) |
Terminal wiring diagram
VM3209K (8 K-type thermocouple inputs)
Terminal outlet wiring method
K-type thermocouple wiring
PT1000 is used for cold junction temperature measurement, so the PT1000 sensor must be connected to the terminal block connected to the K-type thermocouple, as close as possible to the connection point of the K-type thermocouple to reduce the cold junction temperature measurement error.
Thermocouple temperature measurement principle
K- and K+ represent two different metal materials. The A and B terminals are the connection points of these two metal materials and copper and other metal materials. They are located in the normal temperature environment, which is called the cold terminal, and the C point is the measurement point.
Due to the thermoelectric effect, if there is a temperature difference between points A and C, then there will be a voltage difference between points A and C. Similarly, if there is a temperature difference between points B and C, then there will be a voltage difference between points B and C. A voltage difference is generated. Because K+ and K- are two different metal materials, the voltage difference between A and C is not the same as the voltage difference between B and C. Point C is the welding point of K+ and K-. Point C The electric potential is the same, then a voltage difference is formed between A and B, which is the basic principle of thermocouple temperature measurement.
If you want to accurately measure the temperature t1 at point C, you must accurately measure the temperature t0 between points A and B, and t0 is the cold junction temperature. HJ5209K series equipment uses high-precision PT1000 platinum resistance to measure the temperature t0 between points A and B.