The HVB422C4 RS422 Data Port Expander expands a single VideoBloX RS422 channel into four RS422 channels. The RS422 device recieves data from a master device, such as an HVBCPU, on its RS422 slave communication port. The data is transmitted to all 4 master ports of the unit. Data which is returned from the field devices connected to the
master ports, such as keyboards, is combined and sent out the RS422 slave communication port to the master device.
This provides system installers with the ability to implement larger systems using simple directly connected cables. The Data Port Expander also acts as a repeater. Cascading the units extends communication from the typical 4000 foot (1200 meter) RS422 specification to far greater distances. The cable length from each port is 4000 feet. Each port
supports 32 RS422 devices. Note: The HVB422C4 is non-fault tolerant. If any of the field devices connected to one of
the master channels fails, the communication is rendered ineffective. To maximize the communication reliability, a fault tolerant HVB422FT8/16 should be installed.
When the HVB422C4 unit is used within a VideoBloX system, such as with an HVBCPU or HVBLCPU, as indicated on the unit, power is derived from Pin 6 (PWR+) of the slave channel via an RS422 communication cable. Since the HVB422C4 consumes very little power, an additional external power supply is not required. In the rare case when an HVB422C4 is not used within a VideoBloX system, Honeywell recommends an isolated 9-20 Vac transformer to provide power to this unit. Although DC supply is also usable, a low grade switching power supply may render the HVB422C4 and VideoBloX system defective. Therefore, care must be taken when selecting a DC power supply.
The unit may be powered by 9-20 Vac or 10-28 Vdc. The power consumption is <2VA internal. The fuse is rated at 500mA.
The HVB422C4 receives data from a master device on its RS422 slave communication port. This data is transmitted out all four master ports. Data which is returned from a field device connected to the master ports is combined and sent out of the RS422 slave communication port. The following indicators are provided:
• TX DATA- Indicates transmit activity
• TX ENABLE-this is common to all channels. This indication is active when the transmit function in the master channels is enabled. An internal jumper forces the transmit enable to be on (enabled). Refer to paragrah 3.1.1 for setting the jumper.
• RX DATA - this is independent for each channel. Indicates receive activity.