RAD Data comm operation manual Local Digital Loopback, Remote ASM-20 in Digital Loopback

Chapter 4. Troubleshooting and Diagnostics ASM-20Installation and Operation Manual

3.If Step 2 indicates a fault, and if the modem test described Modem Self Test on page 4-4was positive for both the local and remote modems, the line circuits are not operating properly.

L OC A L

D ATA

TE R M IN A L

	REM
	Pressed
DATA	X M TR
CLK
CLK
DATA R C V R
	LOC AL ASM -20

R C V R

X M TR

REM O TE ASM -20

REM O TE DATA

TE RMINAL

Local Digital Loopback

Figure 4-4 Remote ASM-20 in Digital Loopback

This test is activated by pressing the DIG push button. It loops the received data back to the remote ASM-20. (This test is equivalent to activating the remote loopback from the remote ASM-20 - see Figure 4-5). The operator at the remote end can determine the performance of the local and remote ASM-20 units, and the lines between them.

Note The modem with the pressed DIG push button must be in RCV or ASY mode

REM O TE DATA

TE RMINAL

DATA	XM TR
CLK
DATA	RCVR
CLK
	REM O TE ASM -20

DIG

Pressed

RCVR

XM TR

LOC AL ASM -20

LOC AL

DATA

TE RMINAL

Figure 4-5 Local ASM-20 in Digital Loopback

4-6 Communication Link Tests