Black Box SW926C Appendix a Serial Ports, Merged Printouts, RS-232 and RS-422 Pin Assignments

MODULAR SMART SWITCH

10.7 Merged Printouts

If the output from one computer has been printed in the middle of that from another, you will probably need to increase the timeout period. When no data has been sent from one computer for the timeout period (by default

16 seconds), the Modular Smart Switch will allow another computer to start printing. To change the timeout period, use the control software (see Section 6.10.2) or send a software command (see Section 9.2.4). The default timeout period is set using the option switches on the main board (see Section 4.1).

10.8 Print Data Transmitted but File Transfer Fails

If you can print normally using your PC’s serial port but file transfer fails, check the following:

•Make sure that the control software is installed.

•Make sure that the protocol is set to 8 bits, 1 stop bit, no parity.

•For hardware handshake, make sure that pins 4 and 5 are connected on the Modular Smart Switch end of the computer serial cable.

MODULAR SMART SWITCH

Appendix A: Serial Ports

A.1 RS-232 and RS-422 Pin Assignments

The serial ports on the Modular Smart Switch use DB25 connectors. The following table lists RS-232 and RS-422 pin assignments and signal descriptions. Those pins not appearing in the table are not used.

Table A-1. DB25 Serial Pinouts.

Pin	Description	RS-232	RS-422	In/Out
1	Protective ground (shield)	EARTH	EARTH	—
2	Transmitted data (data out)	TXD		Output
3	Received data	RXD		Input
4	Request to send—Always held HIGH	RTS		Output
5	Clear to send—flow control in	CTS		Input
	(hardware handshake)
7	Signal ground	GND		—
20	Data terminal ready—flow control out	DTR		Output
	(hardware handshake)
9	Flow control out (-ve)—hardware		HSOUT -	Output
	handshake

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