SP236 4-20mA Splitter Saves Splitting Headaches with Loopy Acting Circuits

By Mike M., Inside Technical Sales Representative

The long lived and widely used 4-20mA loop circuit is predominant in the process I&C monitoring and control field, yet due to the differing mix of sensor/transmitters and control/monitoring analog input/output configurations, ground loops, transients and differential grounding can cause the 4-20mA control circuit to act, well, loopy! 

Acromag is well recognized in the industry for our signal isolators and isolated transmitters that provide the isolation and I/O sinking/sourcing parity bridge between sensory analog output and control analog input devices. By far, most signal isolators are for the industry standard 4-20mA control loop circuit, and as devices on the monitoring & control side grow with the advent of today’s increasing remote monitoring technology, the 4-20mA signal is more and more required to split from the sensory input into two duplicating outputs.

Acromag isolators with galvanic circuit separation, TVS transient voltage suppression devices and capacitors provide the 4-20mA loop circuit with exceptional protection against unruly electrically operational environments, however external factors can and do play havoc with the entire sensor to controller or motor drive circuit that cause circuit faults or failures. The loop isolator, being the I/O bridge, will be a first point in diagnostics checkout by the field technical support personnel and having input and output channels indication of a good or bad loop circuit can guide the diagnostics tech to a quicker path to a corrective fix.

Acromag loop isolators and signal splitters have front panel LED indicators to indicate the health of the output loop, and with our software configurable SP236-0600 two-wire output loop powered 4-20mA splitter, built in Namur input loop monitoring range limits can be set in the configuration software to transmit input fault status on the output loops. This means from the controller and monitoring device, an under/over range loop current signal can notify the system of an issue with the sensor device connected to the SP236 input including a lead break. This gives the operator or automated monitoring system the ability to recognize a 3.7mA under range value on the 4mA low side and a 20.7mA over range on the 20mA high side of the 4-20mA current loop control signal and make corrective actions.

The Acromag SP236 4-20mA signal splitter allows for not only standard Namur NE43 low/high output limit settings but also the ability to set you own limit indications as desired. The same input loop monitoring Namur or user defined limit settings are available on Acromag’s NEW DT236 dual-channel 4-20mA loop isolator that has independent transmitters in one housing that can also be wired to function as a 4-20mA signal splitter.

Only need a single 4-20mA isolator transmitter but would like input loop health indication on the output loop? Acromag’s TT236 single channel 4-20mA loop isolator is software configurable for input loop signal out-or-range indication including broken lead detection.

Acromag continues to design-in value added features to our process signal isolators, transmitters, limit alarms and network I/O products to give our valued customers more functions along with the built-in quality Acromag products are know for for over 60 years.

Whether you are upgrading an existing I&C system requiring 4-20mA loop isolators or designing a new system complete with IIoT remote monitoring where multiple 4-20mA outputs are needed, save yourself those splitting headaches troubleshooting loopy circuits and look to Acromag for quality signal isolation and software input monitoring features.

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