C-40
Preliminary November 4, 1998
MAX 4000 Series Hardware Installation Guide
Cables and Connectors
Serial host interface specifications
Cable length requirements
Table C-29 specifies the recommended maximum length of the cable between the MAX and
the serial host equipment. Longer distances at the specified data rates are possible when you
use terminal timing. If you require still longer distances you can install the Ascend RPM, a
hardware device that provides an extended-distance high-speed link between the MAX and the
serial host equipment.
6
RX/SEL
I(B)*
RX/SEL
SGND*
20, 28**
25***
12***
7
B(A)
B(B)
BT+
BT-
18
19
7
14
8
C(B)
8, 10****
*
Both I (B) and G connect to SGND, pin 25 on DB-44.
**
Pins 20 and 28 on the DB-44 interface are jumped together.
***
Connect pin 25 (DB-44) to pin 12 (DA-15) through a 200 ohm resistor.
****
Connect pin 8 (DA-15) to pin 10 (DA-15) through a 200 ohm resistor.
Table C-28. Pinouts for X.21 cable to generic serial host (continued)
Model Number MBHD-X21
Part number 2510-0098-001
Pair #
X.21 signal name
(MAX)
Equivalent V.35/RS-449
signal name
(MAX)
MAX male DB-44
(MAX)
Host female DA-15
Table C-29. Cable length requirements
MAX cable length
Serial data rate
25 feet
3 Mbps
75 feet
2 Mbps
150 feet
512 Kbps
