Intelligent Weighing Technology IDC Series Setup And Operation page 15

a. How the COM Validation "Loopback" Testing works.
i. Loopback testing is a commonly used bidirectional RS232 communication test
ii. The loopback device connects the RS232 transmitted line to the received line.
iii. Typically loopback failure is caused by physical connection fault, though
b. Cautions when using RS232 extension cables with scales.
i. The loopback device can be put at the other end of added straight through
ii. If a null modem cable is used by mistake as RS232 cable extension, the CTS
Appendix C - Free download of test software for scale RS232 Communication
ComTestSerial (CTS) is available as free download from MicroRidge Systems Incorporated.
CTS is terminal emulator software, which may be for used for testing bidirectional RS232 on scales. It
is a handy and very user-friendly replacement for Hyperterm, which is no longer included in Windows.
MicroRidge is a trusted long term supplier of commercial connectivity products, including connectivity
software and hardware for use with industrial equipment, test equipment, gauges, and scales. CTS
software and complete instructions can be found on the MicroRidge web site. Download this
software and manuals ONLY from web site, http://www.microridge.com/comtestserial.htm
Intelligent Weighing Technology, 4040 Adolfo Road, CA, 93012 USA
E-mail: sales@intelligentwt.com
from a software application, internally through the computer operating system,
and out to the external physical DB9M connector.
1. The green text is original typed in message - sent from CTS to COM port
2. The yellow text is the same message "echoed" back from the DB9M end
of the COM or VCOM port by the loopback device.
1. The message is seen by CTS, as a new message from an external device.
2. Strictly this test works for any RS232 setting in CTS, since the same CTS
setting are used for both sending and receiving.
3. But since CTS was set to scale setting before testing, passing means
RS232 link has been independently validated for the COM or VCOM port
to application software on same settings needed for scale to MBS link.
embedded system faults can also be cause.
RS232 cables extensions - for COM Validation over cable extensions.
Test 2 and loopback device will NOT detect this fault.
1. A null modem extension cable will pass CTS Test 2 - but fail CTS Test 1.
2. The mistaken use of a null modem cable extension can be confirmed by
the addition of a null modem adapter, which will restore the correct signals
to the correct RS232 connector pins.
Page 15 of 15 - TD0116 RevA01 11-30-2016RP
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