8 to 56 channel HART to MODBUS Multiplexor

Operation
The HtMux is a HART fieldbus gateway device that interfaces a network of HART compatible devices to a MODBUS Host computer. System configuration features provide optimum setup for many different control schemes and system requirements.

The primary function of the HtMux is to poll Hart transmitters, and provide Real Time Process Variables in their original IEEE floating point format or in scaled integer format. A Host device will read the process variables from the HtMux using standard MODBUS Read commands.

Upon power up, the acquisition of the Process Variables (PV’s) from each of the HART devices connected to the HtMux is done in REAL TIME regardless of the number of channels configured. Each channel is fully HART conformant with regards to Primary and Secondary master network timing parameters.

Two MODBUS RTU serial communications ports are provided by the HtMux for interfacing to a MODBUS Host computer system. Both ports operate independently of each other. For instance, one port may be connected to the primary control host MODBUS device while the other one is connected to a maintenance computer system. For very high throughput applications, both MODBUS slave ports can be polled to double the effective data throughput. Alternatively, the Ethernet option is able to provide extremely high throughputs to host devices. Full multi-session support is available, allowing multiple hosts to connect to the Ethernet port at the same time.

The secondary function of the HtMux is to provide an interface to the non-real time or static database information  that may be of use in the control, data acquisition , or maintenance scheme. Through the use of data TEMPLATES, the MODBUS Host machine can have access to any definable data item in any of the transmitters in the system, including those which are only accessible using device specific commands.