METSO Isolated Input Module IOP301

LED Indication

A green LED, labeled Active at the bottom of the module front panel, is on when system power is present and the module is communicating with the DPU. This LED blinks on and off at a constant rate when the module is not being scanned by the DPU.

Bus Address

This module supports two modes of operation selected by jumper setting. For use as a replacement for a Model 564 module this module requires 16 bus addresses and provides 15 channels. The addressing rules specified in the Model 564 manuals still apply. When used as a maxPAC module, the module only requires two bus addresses and provides 16 channels.   Each module address must be on an even boundary (i.e. 32, 34 50 etc.) in the range of 32 to 252.    Addresses 0 to 31 are reserved for digital input modules.

Jumper Configuration

The module contains two jumpers. Refer to the following table for jumper setting information.  

Module Operation

This microprocessor-based module supports up to 16 4-20 mA inputs, all powered from a local 24V loop supply. A sigma delta A/D and reference are provided for each input. Each A/D constantly reads the voltage generated by the input and converts the differential measurement to a 15-bit plus sign binary value, which is read by the microcontroller.   The digital filter in the oversampling A/D provides excellent 50/60 Hz normal mode rejection. Immediately following each measurement, open input and over range conditions are checked. A DC/DC converter provides isolated power to the A/D measuring circuit. Communication between the microcontroller and the A/D is serial at 100kHz. Optical isolators provide the isolation between the A/D and the serial logic circuits.   The microprocessor provides the input data to the DPU on demand via the bus FPGA. The FPGA provides the I/O bus interface logic; its program is loaded from the FLASH on power up. Module calibration is done automatically at power up following startup diagnostics. Calibration is repeated periodically online to compensate for temperature effects.