B&B Electronics 232D4SS8 manual Binary File Transfer, Port Select Test

soon as the CTS line on port A was lowered. At that time any of the other RS-232 ports on the 232D4SS8 can raise their CTS line to establish connection. If port A is connected to the Master port and any of the other RS-232 ports on the 232D4SS8 raises their CTS line, the data sent to the 232D4SS8 from those ports would be lost. The 232D4SS8 does not have buffering.

Note that when a port is selected via the Master port, the CTS lines will be ignored until the Smart Switch receives the turn off command from the Master port. When a CTS line selects the Master port, all commands will be ignored until CTS goes low.

A typical application would be to tie CTS & RTS together on the Master port. So when CTS on a port is raised, RTS on that port also goes high establishing a connection for your hardware. Note that RTS will be low until connection to the Master port has been completed. The other ports will be held off because TD, RTS, and DTR will be low. After CTS goes low, the 232D4SS8 will scan the CTS lines starting with the next port. When there are no ports selected Port A will have first priority, port B second and so on.

Binary File Transfer

A simple method of using the Smart Switch to transfer binary files without the concern of it accidentally disconnecting, is to set the file transfer at a baud rate different from the baud rate of the Smart Switch. When transferring files at a different baud rate, the Smart Switch will stay connected from the last command control string.

Port Select Test

The 232D4SS8 has a built-in port select test. Placing DIP switch 1 (SW1) position 8 in the on position and powering up the 232D4SS8 starts this test. Refer to Figure 2. It will test the port selection, and address circuits for all eight ports. When the test is started each port will be individually turned on for one second, starting with port A on the 232D4SS8 and ending with port H for a total test time of eight seconds. Once the last port has been turned off the test will start over and continue looping until SW1 position 8 is placed in the off position, at which time the Smart Switch will begin normal operation. This test is can be used to verify address settings of the port expander modules.

Documentation Number 232D4SS84502 Manual 17

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