Board Configuration

The board provides jumper blocks to configure the following functions.

  • Serial port protocol RS-232/422/485/TTL: 2 positions for each port.

  • RS-422/485 RX and TX termination: 4 positions for each port.

  • RS-485 echo yes/no per port: 1 position for each port.

  • PCI slot ID: 2 positions for slot 0-3 selection.

  • For hardwired configuration, locations are provided on the PCB for 0-ohm resistors to be installed to replace each valid jumper position.

    Serial Protocol Selection

    Jumper blocks J7 through J14 are used to select the protocol for each serial port, as shown in the table below. Each jumper block configures one port, and each port may have its protocol set independently of the other ports.

    Jumper Port
    J7 1
    J8 2
    J9 3
    J10 4
    J11 5
    J12 6
    J13 7
    J14 8

    In RS-422 or RS-485 networks, termination resistors are normally installed at the endpoints of the cables to minimize reflections on the lines. Emerald-MM-8Plus provides 150Ω resistors for this purpose. To enable resistor termination for a port, install jumpers in the locations T and R of that port’s corresponding configuration jumper block as shown, below.

    Note: Termination is only needed, and should only be used, at the cable endpoints. Enabling these termination resistors at each end of the cable results in an effective impedance of 60Ω. Installing termination resistors at additional points in the network may cause overloading and failure of the line drivers due to the lower impedance caused by multiple resistors in parallel.

    In RS-422 or RS-485 networks, biasing resistors are normally installed at the endpoints of the cables to force a known inactive state on the lines to reduce noise and eliminate line float by pulling the Data+ line to +5V and the Data- line to ground. Emerald-MM-8Plus provides 4.7KΩ resistors for this purpose. To enable resistor termination for a port, install jumpers in the locations B of that port’s corresponding configuration jumper block as shown above. For RS422 networks the RX termination always has biasing resistors connected when used and the TX termination has the biasing resistor connections optional when used.

    Note: Biasing is only needed, and should only be used, at one of the cable endpoints. Installing biasing resistors at additional points in the network may cause overloading and failure of the line drivers due to the lower impedance caused by multiple resistors in parallel.

    RS-232 Selection

    Figure 1 shows the J7 through J14 jumper settings to select the RS-232 protocol. (No pins are jumpered).

    Figure 1: RS-232 Protocol Selection




    RS-422 Selection

    Figure 2 shows the J7 through J14 jumper settings to select the RS-422 protocol options.

    Figure 2: RS-422 Protocol Selection Options




    RS-485 Selection

    Figure 3 shows the J7 through J14 jumper settings to select the RS-485 protocol options.

    Figure 3: RS-485 Protocol Selection Options




    PCI Slot ID Selection

    Jumper block J6 sets the PCI slot ID using two jumpers, as shown in Figure 4. Take care in selecting the correct PCI slot to avoid resource conflicts in the software driver.

    Figure 4: PCI Slot ID Selection Jumper