
V1.3 | ELSETA | Introduction
1. Introduction
IOMod 8AI is a compact-sized stand-alone Modbus (RTU) or IEC-60870-5-103 analog input
controller. IOMod can be used for industrial applications where digital signaling is used and robust
communication is needed. IOMod is an ideal solution for applications such as data acquisition,
observation, process monitoring, testing and measurement at remote places. It is controlled over
Modbus or IEC 60870-5-103 protocol, and can be used with any SCADA system.
2. Features
● 8 analog inputs, each configurable separately
● All inputs are capable of measuring electrical voltage or current
● Inputs can be recalibrated according to the needs of a user
● RS485 communication
● LED input indications, + Data transmission (Rx and Tx) indication.
● Configurable over USB
● Drag-and-Drop firmware upgrade over USB
● A small sized case with removable front panel
● DIN rail mount
● Operating temperature: from -30 to +70°C
● Power Requirements: 12-24 VDC
3. Operational information
IOMod 8AI uses Modbus (RTU) or IEC 60870-5-103 protocol over RS485 interface. A protocol used
by a device can be changed by uploading corresponding firmware. Default communication settings:
9600 baud/s baud rate, 8N1 port configuration, Slave address - 1.
a. Common configuration information
1. Measurement type. A user can select measurement type (electrical current or voltage) on each
channel individually.
2. Sensitivity selection. To increase a resolution of input measurement capture, a user can define
in which range measurement will occur. The best resolution will be achieved within a shortest
selected range. For all possible configurations refer to Technical Information and
Configuration over USB described later in this document.
3. Measurement limits can be selected, which in turn set thresholds on underflow or overflow error
statuses. Also, if a scaled integer data type is selected, these limits will be converted to values
using limits stated in Casting data range for Modbus protocol.
4. Data type selection. A device can output float or scaled integer data types for each input
individually for Modbus. Modbus input register read will then show raw float value (in
milliamperes or millivolts) or scaled integer types. When a float data type is selected, each input
will be represented as two Modbus registers (32-bits). These values can be later converted to