EIA530 (RS530) interface

RS530 is just like RS422 and uses a differential signaling on a DB25 - RS232 format - EIA-530 Transmit (and the other signals) use a twisted pair of wires (TD+ & TD-) instead of TD and a ground reference as in RS232 or V.24. This interface is used for HIGH SPEED synchronous protocols. Using a differential signaling allows for higher speeds over long cabling. This standard is applicable for use at data signaling rates in the range from 20,000 to a nominal upper limit of 2,000,000 bits per second. Equipment complying with this standard, however, need not operate over this entire data signaling rate range. They may be designed to operate over a narrower range as appropriate for the specific application.

Pin	Name	Dir	Description	Circuit	Paired with
1			Shield		18
2	TxD		Transmitted Data	BA	14
3	RxD		Received Data	BB	16
4	RTS		Request To Send	CA	19
5	CTS		Clear To Send	CB	13
6	DSR		Data Set Ready	CC	22
7	SGND		Signal Ground	Ground	21
8	DCD		Data Carrier Detect	CF	10
9			Rtrn Receive Sig. Elmnt Timing	DD	17
10			Rtrn DCD	CF	8
11			Rtrn Transmit Sig. Elmnt Timing	DA	24
12			Rtrn Transmit Sig. Elmnt Timing	DB	15
13			Rtrn CTS	CB	5
14			Rtrn TxD	BA	2
15			Transmit Signal Element Timing	DB	12
16			Rtrn RxD	BB	3
17			Receive Signal Element Timing	DD	9
18	LL		Local Loopback	LL	1
19			Rtrn RTS	CA	4
20	DTR		Data Terminal Ready	CD	23
21	RL		Remote Loopback	RL	7
22			Rtrn DSR	CC	6
23			Rtrn DTR	CD	20
24			Transmit Signal Element timing	DA	11
25			Test Mode	TM

Note: Direction is DTE (Computer) relative DCE (Modem)