Table of Contents
4-Channel Analog to Digital Input Module: MD-ADIN4
The AD Input Modules can be wired to read voltage sources or current sources.
When reading voltages sources, the modules can be configured for a 0 ~ 10V range or a 1 ~ 5V range using the dipswitch on the side of the module.
When reading a current source (4-20mA), connect a 250 ohms resister across the input terminals.
The input voltage range can be adjusted using dipswitch #2. Dipswitch #1 is not used.
Specification
| Item | Description |
|---|---|
| Channels | 4 |
| Operating Temperature | -10 ~ 50 (no condensation) |
| Operating Humidity | 35 ~ 85%RH |
| Input Resistance | 20K ohms |
| Input Voltage Range | 1~5V mode: 0.5 ~ 5.5V (Single-ended) 0~10V mode: -0.5 ~ 10.5V (Single-ended) |
| Output Value | 0 ~ 10,000 |
| Resolution | 13.3-bit |
| Precision | ±0.1% |
| Conversion Speed | 30ms per channel |
| Communication Method | RS485 |
| Packet Transmission | 3ms |
| Isolation Method | No Isolation |
Important: The AD Input Modules' inputs are not isolated, so please be sure to not provide voltage or current in excess of the specified ranges. Doing so could cause permanent damage.
When the system is first powered on, all four channels are scanned once. Reading at this time will return an invalid value. Please allow at least 120ms from the time the system is powered on before reading any data.
This module has built in low pass filter and noise canceling circuitry. Since the A/D pins are not exposed, the user is not expected to design additional circuitry.
Output Values
The value returned from the MD-ADIN can be interpreted with the following algorithm:
unsigned short rawData = 0; // Raw 16-bit value from the MD-ADIN int value = rawData; if ((rawData & 0x8000) != 0) // If most significant bit is set { value = (rawData - 0x8000) * -1; } if (value == -11111) { // Value is below the lower bound (e.g. below 1V when 1-5V mode is selected). } else if (value == 22222) { // Value is above the upper bound. (e.g. above 5V when 1-5V mode is selected). } else { // Value is between 0 and 10,000 }
Modbus Starting Address
Each module has 4 channels, each with its own unique Modbus address.
| Channel | 0 | 1 | 2 | 3 |
|---|---|---|---|---|
| Starting Address(base 10) | 100 | 101 | 102 | 103 |
| Starting Address(base 16) | 64 | 65 | 66 | 67 |
| Address (base 10) used by HMI (SCADA) | 40101 | 40102 | 40103 | 40104 |
Module ID (Modbus Slave Address) Assignment
On the front of the module, there is a rotary switch labeled ID, that is used to select the Modbus slave address for the module. When installing multiple modules of the same type, the ID for each module should be unique.
Rotary switch position 0 corresponds to Modbus slave address 10. If the ID is changed after the module is powered on, it must be power cycled for the new ID to take effect.