EAW DSA250i, DSA230i owner manual One path was to the EIA-485 port. So when B responds

EXAMPLE 1: (no figure shown)

One cabling configuration that you should NEVER make is to daisy-chain the EIA-485 cabling from module to module then home run a cable from the last module back to the PC to create a closed loop. This may seem like a good idea because, if there is a break anywhere in the cable, there will still be a connection back to the PC. The key words here are that this will CREATE A LOOP and loops are bad.

PC DSA

PILOT

MESSAGE

FOR "B"

485	CM1	SLink
	DSA "A"
	NO MATCH,
	RESEND
	PLink

EXAMPLE 2:

Here, DSAPilot sends a message to "B". This message requires a response from "B". Just like each DSAi modules, the PC has a unique address.

"B" will get the message from both the EIA-485 connection, and the PLink to SLink connection. Should "B" be required to respond to the message from the PC it will do so through the port or ports through which it received the message.

	485			CM1	SLink	One path was to the EIA-485 port. So when "B" responds,
						back through this port, the PC gets the message but so does
						"A" through its EIA-485 port. "A"'s address won't match
			DSA "B"
						the PC address and so will forward it out its other ports thus
		ADDRESS MATCHES,
		USE IT, REPLY TO PC				sending the message back to "B" through the PLink to Slink
						connection. "B" will respond again this time sending it out
				PLink
						its SLink port to "A". As the message is not for "A", "A"
						sends it out its EIA-485 port to the PC and "B" again. It
Figure 8.6.6a Example 2						responds through the receiving port, now the EIA-485,

back to the PC and "A" again.

The other path for the message was to the SLink where "A" forwarded it. So "B" would also respond through that port and "A" would forward it out the EIA-485 port back to "B", and so on. The network will rapidly become saturated and from DSAPilot's point of view, very intermittent.

CobraNet	ETHERNET
Source	SWITCH

EXAMPLE 3:

PC	485	CM1	SLink
DSA PILOT
		DSA "A"
		PLink

485 CM1 SLink

DSA "B"

PLink

Here is another connection topology using CobraNet audio and EIA-485 computer control with a loop. Looping occurs through the RS485 and CobraNet. Just follow the arrows.

Figure 8.6.6b Example 3

NOTE: See Example 4 in Section 8.6.5 to properly configure this topology or use DSAPilot to configure the Com Settings for Network audio and EIA-485 control. This disables the control connection from the CobraNet card to the EIA-485 bus, thus preventing a control loop through the CobraNet interface.

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