Maple Systems STEPware-100 - Manual (Page 29)

To modify this parameter in Configuration mode:
1. At Stop Bits:, use the OIT’s TOGGLE key to select the desired number of stop bits.
Refer to the Configuration Mode section in this chapter for more information.
To modify this parameter from the host controller:
1. Use the Set Communications Parameters control command. Refer to Appendix A:
Control Commands for more information.
Handshaking Setting
This parameter determines the type of handshaking that is used between the OIT and the
host controller. Handshaking allows the host controller to regulate when the OIT sends
information; preventing the OIT from overwriting the host controller’s serial buffer or vice
versa. Options are software handshaking (Xon/Xoff), hardware handshaking (RTS/CTS),
both, or none. When the OIT is in Configuration mode, no handshaking is used to
communicate to STEPware-100 regardless of how this setting has been configured.
To modify this parameter using STEPware-100:
1. Open the Configuration Editor.
2. In the OIT - Host Serial Communications Settings group box, select the desired
handshaking in the Handshaking list box.
To modify this parameter in Configuration mode:
1. At Handshake:, use the OIT’s TOGGLE key to select the desired handshaking. Refer
to the Configuration Mode section in this chapter for more information.
To modify this parameter from the host controller:
1. Use the Enable Handshaking control command. Refer to Appendix A: Control
Commands for more information.
Software Handshaking
Software handshaking, which uses the Xon/Xoff format, is available only in Interactive
mode. The following rules apply:
1. When the host controller sends an XOFF control code (hexadecimal 13), the OIT
halts transmission of any data to the host controller until the host controller sends an
XON control code (hexadecimal 11). While transmission is halted, each OIT keypress
continues to be displayed on the OIT but no data is transmitted to the host controller.
Instead, each character is temporarily stored in an 8 byte ‘Handshake’ buffer. When
the handshake buffer is full, each OIT keypress causes the OIT to sound a warning
beep. The data continues to be displayed on the OIT but is not stored in the
Handshake buffer. Therefore, the host controller does not receive any data that is
entered when the handshake buffer is full.
2. When the host controller sends the XON control code, the OIT sends the contents of
the Handshake buffer to the host controller before proceeding normally.
3. The OIT has the option of sending the XOFF control code to the host controller if the
host controller is sending data to the OIT faster than the OIT can process it. When the
OIT sends the XOFF control code to the host controller, the OIT ignores any further
transmissions from the host controller until the OIT sends the XON control code. The
OIT has an internal buffer size of 200 characters. When the OIT’s buffer contains 170
characters, the OIT sends the XOFF control code. The OIT sends the XON control
code when the buffer is empty (the time required to empty the buffer varies according
to the baud rate but is approximately 150 msec.).
26 STEP1 Protocol Operation Manual
1010-0096, Rev. 04