Emerson ROC827 EIA-422/485 RS-422/485 Serial Communications Module, Signal LED Function

ROC827 Instruction Manual

The EIA-232 (RS-232) communications includes LED indicators that display the status of the Receive (RX), Transmit (TX), Data Terminal Ready (DTR), and Ready To Send (RTS) control lines.

Table 5-7 defines the built-in EIA-232 (RS-232) terminals at the Comm2 port and their function signals.

Table 5-7. Built-in EIA-232 (RS-232) Signal Routing – Comm2

Signal	LED Function	Terminal
RX	Lit when Comm2 is currently receiving.	1
TX	Lit when Comm2 is currently transmitting.	2
RTS	Lit when Comm2 ready to send is not active.	3
DTR	Lit when Comm2 data terminal ready is active.	4
GND	Common.	5

The EIA-232 (RS-232) communications module provides for EIA-232 (RS-232C) signals on the Comm3, Comm4, or Comm5 port depending on where the module is installed. Refer to Table 5-8.

Table 5-8. EIA-232 (RS-232) Communication Module Signal Routing – Comm3, Comm4, and Comm5

Signal	LED Function	Terminal
RX	Lit when module (Comm3, Comm4, or Comm5) is	1
	currently receiving.
TX	Lit when module (Comm3, Comm4, or Comm5) is	2
	currently transmitting.
RTS	Lit when module (Comm3, Comm4, or Comm5) is	3
	ready to send is not active.
DTR	Lit when module (Comm3, Comm4, or Comm5)	4
	data terminal ready is active.
GND	Common.	5

5.8EIA-422/485 (RS-422/485) Serial Communications Module

EIA-422/485 (RS-422/485) communication modules meet all EIA- 422/485 (RS-422/485) specifications for differential, asynchronous serial communication transmissions of data over distances of up to 1220 meters (4000 feet). EIA-485 (RS-485) communications are commonly used to multi-drop units on a serial network over long distances using inexpensive twisted-pair wiring.

EIA-422 (RS-422) drivers are designed for party-line applications where one driver is connected to, and transmits on, a bus with up to ten receivers. EIA-422 (RS-422) allows long distance point-to-point communications and the drivers are designed for true multi-point applications with up to 32 drivers and 32 receivers on a single bus.

The default values for the EIA-422/485 (RS-422/485) communications are 19200 Baud Rate, 8 Data Bits, 1 Stop Bit, and No Parity. The maximum rate is 57.6K bps.

Issued Mar-06 Communications 5-10