It can access Com ports 1-8, including USB serial devices. Windows 95/98/SE/ME/2000 or NT 4.0: Use ComTest from our Website to check serial ports assigned Com1 or higher under Windows. ComTest (a B&B program) can open two sessions, one to access each Com port being used. If data is received and transmitted in both directions, the port/converters are most likely fine. Next data is transmitted from the second to the first. The Data A(-) line from one converter is connected to Data A(-) on the other, and the Data B(+) from the first is connected to Data B(+) on the second.Ī terminal program is opened to access one port for transmit, another port for receive, and data is transmitted from the first port to the second. While transmitting, receive is disabled, while receiving, transmit is disabled and tri-stated. It either transmits or receives, but not both at the same time. This is because a 2-wire RS-485 port is half duplex. When you have a converter without a Echo On option, you need a second RS-485 port or converter to receive the signal transmitted by the first OR to transmit a signal to be received by the first.
With some converter models Echo can be changed by soldering, but to keep things simple, this procedure does not cover that option. Refer to the Table for a list of models with a easily moved Echo/RX Enable Switch or Jumper. When you're using a RS-485 converter that can be set up for 2-wire or 4-wire RS-485 operation, the RS-485 Receiver can be enabled (Echo On or RS-422 RX Enable) as in 4-wire mode, and the TD(A) & RD(A) connected, and the TD(B) & RD(B) connected as in 2-wire mode, to "loop" the output back to the inputs. This article gives detailed instructions on how to do that in a two-wire system. Have you ever been stuck in the field trying to troubleshoot a faulty system? When communications are suspect you'll want to be armed with information on how to field-test an RS-232 to RS-485 converter. Standmount Embedded Automation Controllers AirborneM2M Embedded Dual Band 802.11 a/b/g/n Wireless ModulesĪirborneM2M 802.11 a/b/g/n Dual Band Wireless
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