The HCI receiving station is composed of two parts: the NSMHC module and the NBTR module. The NSMHC module is enclosed in an aluminium housing and is normally placed inside the control systems cabinet; the NBTR module is enclosed in a plastic pipe and should be placed in a well exposed position to allow for the best radio communication with the H4 handheld device. The connection between the NSMHC module and the NBTR module is achieved with an Ethernet patch (not crossed) cable up to 20m long. The cable shall be a CAT5 shielded Ethernet cable.
The aim of the NMSPM system (Wireless Safety Modules for handheld terminal ) is to establish a safe wireless connection between a cabinet and an handheld terminal (HMI).
The safety of the information is assured by the intrinsic safety of the message flowing thru an unsafe communication media (black channel), while the unambiguous connection between the NC cabinet and the handheld terminal is accomplished by the use of unique hardware keys called TOKENS. Each token holds specific and unique information that are used as part of the message between the NC cabinet and the handheld terminal.
|Coupling Interface TOKEN Connection||USB A receptacle (no physical interface, connector only)|
|BLUEGIGA WT11 (Class 1)|
|Transfer Rate||up to 3Mbps|
|Max working distance||50m|
|RS-422 Serial Interface Transceiver||ISO35 RS-422 Transceiver|
|Transfer Rate||57600 bps|
|Connection||2 twisted pairs (TX+/TX-,RX+/RX-) plus reference ground|
|Power Supply Rated voltage||24 VDC (+/-15%)
Supplied by a SELV or PELV power supply
|Max interruption of the supply||5 ms|
|Power consumption||240mA @ 24V (idle)
2.4A @24V (max)
|Stop push-button related relays||2 contacts. 8A 24Vdc max|
|EnablingDevicerelated relays||2 contacts. 8A 24Vdc max|
|State Selector related Mosfet switches||4 Mosfet switches.24Vdc 500mA each max|
|Outer dimensions Length||180 mm|
|Weight (without cable)||760g|
|0◦ to +55◦C|
|Transport and storage temperature||−20◦ to +70◦C|
A dual safe stop pushbutton provides a duplicated normally closed contacts that are opened whenever the pushbutton is pressed. The state of the dual closed contacts is continuosly monitored by the SMWL module and separate test pulses are used to check for short circuits. On the SMHC module a couple of safe relays keep their N.O.contacts closed only when the information received by SMWL are formally correct and report that both input contacts are closed.
Enabling Device Handle
A dual safe enabling device provides a duplicated normally open contacts that are closed only when a right pressure is applied to the handle. The state of the dual closed contacts is continuosly monitored by the SMWL module and separate test pulses are used to check for short circuits. On the SMHC module a couple of safe relays keep their N.O.contacts closed only when the information received by SMWL are formally correct and report that both input contacts are closed.
State Selector Rotary Switch
A 16 position rotary switch provides a binary coded 4 bits output. The switch has a common pin and 4 output pins. Each one of the 4 output pin is connected to the common pin or left open according to the binary code that represents the mechanical position. The closed contact state of the 4 pins is read by the SMWL module and the information transferred to the SMHC module. On the SMHC module, 4 high-side mosfet switches provide a positive 24V voltage for every corresponding pin that is closed on the rotary switch. Each digital output is fully diagnosed by a feedback circuit and test pulse.
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