Automatic Handshake Control for RF Modems with RS-422/485 Conversion Many low cost or older radio data links require that RTS be raised from the serial device to enable the radio's transmitter. This can be a problem for RS-232 devices with no handshake control or RS-422/485 systems where no handshake lines are typically present. The Model BAMHC solves this problem by providing hardware handshake control for radio frequency and other modems requiring the RTS line to control the transmitter. The BAMHC allows the use of legacy or low cost systems without the expense of updating to modems with buffering or built-in RS-485 interfaces. RS-232, RS-422, or RS-485 data signals at up to 19.2 Kbps are supported. The BAMHC raises RTS and buffers up to 160 characters while waiting for the modem to be ready to transmit. The amount of time data is buffered is user-selectable for 5, 10, or 50mS. Alternatively, the modem's CTS line can be used to indicate ready to trasmit. The BAMHC supports both the Transmit and Receive data lines, and the built-in microprocessor provides hardware control of the RS-422/485 driver. The BAMHC enables the driver when it first sees data from the modem. It waits 10 bits after transmission is complete, then disables the RS-422/485 driver. All connections to the host device are provided on the same DB25 male. The unit is powered by 12 VDC and requires 60 mA max. Specifications - Transmission Mode: Asynchronous, half or full duplex
- Host Interfaces: RS-232, RS-422, or RS-485
- Modem Interface: RS-232
- Data Rates: 1200, 2400, 4800, 9600 or 19.2K bps
- Data Formats: 7 or 8 bits; Even, Odd, or No parity (7-N-1 not supported)
- Time to Transmit: User-selectable for 5mS, 10mS, 50mS or wait for CTS
- Host Handshaking: RTS/CTS or None
- Connectors: Host, DB25 Female; Modem, DB25 Male
- Power Supply: Requires 10-16 VDC @ 60 mA max. Can use optional 232PS Power Supply.
- Dimensions: 4.1"L x 2.3"W x 0.95"H
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