EM1500 User’s Manual
109
Q:
I am restarting a telnet connection. Why is it now refusing a connection?
A:
If you cancelled a previous telnet connection to the EM1500, the EM1500 may not know that
the other end terminated, at least not straight away. Normally, you will be able to reconnect
within a few seconds if the previous connection is terminated normally. If the connection is
terminated abnormally by the PC side, then the EM1500 may not know about it until it tests
the connection status again. If there is no incoming (serial) data, then it may not test the
network connection for a long time. The default retesting time is two hours (mandated by
Internet standards). If you want to shorten the connection testing time interval, set a lower
value in the “Connection keepalive” field of the General tab.
Also, in a pinch you can manually disconnect the EM1500 from a “dead” connection by
pressing the “Conn” button on the status panel. The Conn button will be yellow if it is (or
thinks it is) currently connected.
Serial ports
Q:
Why am I getting garbage instead of data?
A:
Check your serial port settings. Are they the same on both sides of the connection? The baud
rate, character size, parity setting and number of stop bits set for the serial port of the EM1500
must match those set for the attached serial device.
For SER3 and SER4 , also check the jumper settings for JP2 and JP3 to make sure they are
set to the correct drive levels, i.e., RS232 or TTL. If the settings are incorrect, the unit may
appear to be receiving an infinite stream of null bytes.
Q:
Why do the connectors for serial ports 1 and 2 have different genders?
A:
Because serial port 1 (SER1) is wired as a DTE and serial port 2 (SER2) is wired as a DCE.
Refer to the diagrams in Section 4.3, “Connector Pin-Outs.”
Q:
Why am I not receiving data from my serial device to the EM1500?
A:
There are several things you can check. First the obvious things: do you have a working serial
cable? Is it the right type (straight-through or null-modem)? Have you supplied power to the
EM1500 and the serial device?
If all of that checks out, turn your attention to the status /debug area of the configuration
program or, using a web browser, contact the EM1500 at its IP address and look at the Status:
Connections page.
Both of these areas show status information for the separate lines of the serial ports. For
example, a particular LED will flash when data is received from SER1. There are buttons and
LEDS for all of the transmit and receive lines, as well as the modem control lines. For details
about this useful debugging tool, please see Section 5.1.11, “Status/Debug Area,” on page 66.
Summary of Contents for EM1500
Page 14: ...10 www rabbit com Introduction...
Page 22: ...18 www rabbit com Getting Started...
Page 76: ...72 www rabbit com EM1500 Configuration...
Page 90: ...86 www rabbit com EM1500 Specifications...
Page 104: ...100 www rabbit com Serial and TCP Protocols...
Page 118: ...114 www rabbit com EM1500 FAQ...