Black Box ME475A-R2, Manual

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Black Box Short Range Modem
the load (or resistor) of the ME475A-R2 unit. Thicker gauge cables requires a lower
ohm setting, while a thinner gauge cable should receive a higher ohm setting. If you
are using higher speeds you will need a lower ohm setting, and a higher ohm setting
for the slower speeds. Refer to Table 5 for assistance in selecting a setting.
Table 5:
S3-1, S3-2 Selection Table for ME475A-R2
Switch S3-4: Mode Selection
The setting for switch S3-4 allows the user to choose the appropriate setting for point-
to-point or multipoint applications.
Switch S3-5: RS-232 Initiation of Local Loopback Test
The setting for switch S3-5 determines whether or not the ME475A-R2’s local analog
loopback test can be initiated by raising pin 18 on the RS-232 interface.
S3-1 S3-2 Setting
On On 130 ohms
On Off 200 ohms
Off On 320 ohms
Off Off High impedance (minimum 2k ohms)
S3-4 Setting
On Point-to-point
On Multipoint application as “Master”
Off Multipoint application as “Slave”
S3-5 Setting
On RS-232 initiation enabled
Gauge of
Cable
19AWG/.9mm
22AWG/.6mm
24AWG/.5mm
26AWG/.4mm
1.2
320
320
320
320
Data Rates, kb/s
1.8
320
320
320
320
2.4
200
320
320
320
3.6
200
200
320
320
4.8
200
200
200
320
7.2
200
200
200
200
9.6
200
200
200
200
14.4
130
200
200
200
19.2
130
130
200
200
28.8
130
130
130
200
38.4
130
130
130
130
57.6
130
130
130
130