Omega Engineering Universal Remote I/O Modules
HE359 Series Universal Remote I/O Modules provide remote I/O for programmable logic controllers (PLCs). Omega Engineering HE359RTD100:
• Connects via 2-wire RS-485 Modbus (RTU or ASCII) to any programmable logic controller (PLC);
• Offers up to 31 I/O modules daisy-chained on one RS-485 link;
• Is DIN-rail mountable;
• Has optical isolation;
• Includes response time suitable for most analog applications;
• Has cost effective addition per point;
• Fits in the smallest panels: 17.5 x 100 x 120 mm (0.69-in. x 3.94-in. x 4.72-in.); and
• Has 12 I/O modules from which to choose, including dc in, relay out, analog in, analog out, RTD, thermocouple.
Remote I/O, or distributed I/O, offers several advantages over the traditional local I/O found on a programmable logic controller (PLC).
First, it allows locating the I/O modules close to the process that is being monitored or controlled. This greatly improves noise immunity, as the weak sensor signals are converted to digital signals before being transmitted long distances through a noisy plant environment. Omega universal remote I/O modules use a simple 2-wire RS-485 link using Modbus RTU/ASCII protocol, which is supported by most programmable logic controllers.
A second advantage is that remote I/O greatly reduces the wiring at the main control panel, saving time and money when repairs and upgrades are necessary. Adding additional sensors and control signals is as easy as connecting to the already installed RS-485 link and modifying the PLC program to use the new I/O connection.
In addition, remote I/O allows expansion of a process control system beyond the local I/O capabilities of your PLC. You can add thermocouple, RTD, pressure, and flow sensors to a PLC that doesn’t support these types of inputs. With remote I/O, your process application is no longer dependent on your controller choice. www.omega.com/ppt/pptsc.asp?ref=HE359&nav=AUTW01
– Edited by Mark T. Hoske, editor in chief, Control Engineering , www.controleng.com.