MOD4205 type 

 Current loop voltage serial measurement head 
 --- The world's smallest Modbus measurement module 
 First, use 
 Boshi current loop voltage serial measurement head (Model: MOD4205) for measuring 4-20mA current loop and voltage 0-5V and RS-232 or RS-485 serial port to the computer or PLC display. MOD4205 with Modbus protocol directly display the measurement results, including a variety of configuration software, Modbus debug wizard, and with Modbus protocol VC, VB, measurement software, etc., you can use any standard software follow the Modbus protocol. Standard output signal is a typical 4-20mA current loop and 0-5V voltage sensors, transmitters, so MOD4205 particularly suitable for the measurement sensor, the transmitter signal. 
 MOD4205 with RS-232 and RS-485 interface. RS-232 port the MOD4205 direct the computer's RS-232 port, easy to use. RS-485 to extend the communication distance to 1200 meters, as well as address setting: four DIP switches can be set up to up to 16 addresses, that is, with a RS-485 bus can take up to 16 MOD4205. RS-485 port can be connected to the PLC Modbus protocol or the Boshi RS-232/RS-485 converter to the computer RS-232 port. 
 Second, the installation and performance 
 MOD4205 the shape of the DB-9 (hole) / DB-9 (pin) size of the adapter box with terminal board. The MOD4205 is the world's smallest Modbus measurement modules, but also the most simple Modbus measurement modules. MOD4205 built-in 10-bit A / D, which is equivalent to a resolution of 0.4%, the sampling rate due to the limitations of the serial communication baud rate 9600bps less than 1K. 
 The left side of the product DB-9 (holes) for the RS-232 port, can be directly extrapolated the computer's RS-232 (pin) port. On the product side of the RS-485 port and an external power supply terminal. Supply voltage of DC 5V to 24V can power consumption less than 100mA. The product is equipped with miniature switching power supply. The under side of the product of four DIP switches for setting the address. DIP switch settings: 4, OFF, 1, ON, near the DB-9-hole side of the high. For example, the products shown on the DIP address 0001. 
 The product of the right side of the DB-9 (pin) with a terminal board for the connected 4-20mA current loop, 0-5V voltage. Terminals 0,1,2,3 Road, the default is used to measure the 4-20mA current loop; 4,5,6,7 the Lu default used to measure the 0-5V voltage. The terminal also provides a ground GND terminal and power supply + V-terminal. + V terminal and RS-485 terminal next to the + V terminal conduction, external power supply. 
 Third, the communication format and software use 
 MOD4205 with Modbus protocol, you can use any software with Modbus protocol to operate. MOD4205 use Modbus-RTU protocol on the 3rd operation (read register). 
 MOD4205 used Modbus format is as follows: 
 3.1 The serial communication parameters 
 Format (9600, N, 8,1), RS-232 port and RS-485 statements to select, supports the standard Modbus RTU protocol. 
 3.2 The device address is set 
 4 DIP switch for device address is set to the OFF side (to the digital side of the 1234) on behalf of this bit is 1, to the ON side (products), the bit is 0. Note that the new settings after the need to re-add power. The setting is as follows: 

 4321 address 16 hex address 10 hex 
 -------------------------------------------------- - 
 0x00 0 0 0 0 0 
 0x01 1 1 0 0 0 
 0x02 2 1 0 0 0 
 0x03 1 1 0 0 3 
 0x04 0 1 0 0 4 
 0x05 0 1 0 1 5 
 0x06 1 1 0 0 6 
 0x07 1 1 1 1 7 
 0x08 1 0 0 0 8 
 0x09 1 1 0 0 9 
 0x0A 1 0 1 0 10 
 A mix of 0x0B 11 1 0 1 1 
 1 1 0 0 0x0C 12 
 0x0D 1 1 0 1 13 
 1 1 1 0 0x0E 14 
 1 1 1 1 0x0F 15 

 3.3 8-channel analog acquisition results storage address assignment: 
 0x0000 --- channel CH0 measurement results 
 0x0001 --- channel CH1 measurement results 
 0x0002 --- channel CH2 measurement results 
 0x0003 --- channel CH3 measurement results 
 0x0004 --- channel CH4 measurements 
 0x0005 --- CH5 measurement results 
 0x0006 --- channel CH6 measurement results 
 0x0007 --- channel CH7 measurement results 

 V1.024 commonly used Modbus Test Wizard for example. If the device address is 0x01 to read the measured values ??of CH0. 
 Connect to the computer's RS-232 or RS-485 port, press the "Open the serial port. "Device address" fill in "1" (the address is 0x01), fill in the register address "0" (for measuring CH0), "number of" default "1". 


 Press "read", as shown in Figure you can see the "hex:" (1370) and the decimal display: "(4976), the measurement results, the unit mV. As the MOD4205 the current loop measurement of the opposite of terminal board 250 ohm sampling resistor, so the measurement results of the current loop 250 ohm sampling resistor voltage. If the user asks for all the measured current loop or all of the measured voltage can be welded on or remove the corresponding channel sampling resistor. 
 The Boshi can be presented the MOD4205 measurement procedures written in VC, VB source code, for professional users only reference.