Motorola 326X V.34 - Manual (Page 178)

B-10 Cabling and Interface Pinouts
Inter
face
Pinout
s
DTE Cable Diagnostics
This section helps determine whether there is a problem with a DTE cable. Perform
the following steps before continuing with installation. If you continue to experience
problems with data transmission after choosing a cable and running the diagnostics
in this section, the problem may be with your DTE or modem.
If the modem is not installed at a host site, perform the following steps:
1) Enable the AT ACU (if not already enabled) with async echo on (reinitializing
the modem will also enable the AT ACU with async echo set to on). Ensure
that rate and parity of the modem and the DTE are identical.
2) Send data to the modem from the DTE. NOTE: Do not substitute test
equipment for the DTE, as the DTE’s receivers/drivers are used in this test.
3) If echoed data from the modem (as received by the DTE) matches the
transmitted message, send the status screen (AT * ST) command.
4) If there are no errors in either of the previous tests, the cable is appropriate for
your application.
Table B-6.
Vendor Wire for 326X
Vendor
Part
Number
Conductor
Capacitance
(pF) Shield
Capacitance
(pF)
Up to 19.2
kbps (ft) Up to 64.0
kbps (ft) Up to 96.0
kbps (ft)
Up to
115.2
kbps (ft)
Belden 9948 35 63 24.49 9.18 4.08 2.04
9671 30 55 28.24 10.59 4.71 2.35
8125 12.5 22 69.57 26.09 11.59 5.80
9937 12 22 70.59 26.47 11.76 5.88
8155 11 20 77.42 29.03 12.90 6.45
Manhattan M39026 33 65 24.49 9.18 4.08 2.04
M13201 30 50 30 11.25 5.00 2.50
M2414 26 47 32.88 12.33 5.48 2.74
M3431 12.5 22 69.57 26.09 11.59 5.80
M2434 12 22 70.59 26.47 11.76 5.88
Madison 25QF10BTI 14.6 26.3 58.68 22 9.78 4.89
25QF15BTI 12.4 22.4 68.97 25.86 11.49 5.75
NOTE: To determine cable length, add the conductor and shield capacitance specified above to determine the total
wire capacitance. For example, if you are using a Belden wire (Part Number 9671), add the conductor capacitance of
30 pF/ft and the shield capacitance of 55 pF/ft for a total capacitance of 85 pF/ft. If you are operating at a rate of 19.2
kbps, the maximum allowable cable length to attain throughput of 19.2 kbps is 28.24 feet. Multiplying 28.24 by the
total cable capacitance of 85 pF/ft yields a maximum allowable cable capacitance of 2410.4 pF, which is acceptable in
accordance with Table B-4.