2head - dte cable diagnostics, Dte cable diagnostics, B-10 – Motorola and V.32bis User Manual
Page 178: Table b-6
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<CR>) 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.