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Community Member

dte signal on serial interface

hi,

i have (perhaps) a silly question:

we have a enddevice which connects over a serial cable to a routers serial interface (enc x25).

the problem is, that the cable between has no pin 20 (dtr) and so the connection does not work because the router needs the dtr.

is there any possibility, that i "switch on" the dtr in the ios software?

i mean - perhaps - a interface command, which turns on dtr or that the router ignores dtr?

thanks for any answer

7 REPLIES
Hall of Fame Super Gold

Re: dte signal on serial interface

The command is exactly that, ignore dtr. Note you need a dce cable for what you want to do, (show controllers serial to know which cable you've currently).

Hope this helps, please rate post if it does!

Community Member

Re: dte signal on serial interface

hi,

thanks for answer - this would be exactly that, what i want and need - BUT:

!

r-altmuen1#sh controllers Serial0/0/0

Interface Serial0/0/0

Hardware is GT96K

DCE V.11 (X.21), clock rate 64000

idb at 0x456ECCF8, driver data structure at 0x456F4414

wic_info 0x456F4A18

!

interface Serial0/0/0

description r-altmuen1: to x.25 Datus (S0/0/0)

bandwidth 64

no ip address

encapsulation x25 dce

load-interval 30

x25 htc 20

x25 win 7

x25 wout 7

clock rate 64000

!

r-altmuen1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

r-altmuen1(config)#interface Serial0/0/0

r-altmuen1(config-if)#ign

r-altmuen1(config-if)#ignore ?

dcd ignore dcd

r-altmuen1(config-if)#ignore dcd ?

dsr ignore dcd dsr

r-altmuen1(config-if)#ignore dcd dsr ?

r-altmuen1(config-if)#ignore dcd dsr

This command is not supported on this interface

r-altmuen1(config-if)#

Cisco 2821 (revision 53.51) with 237568K/24576K bytes of memory.

Processor board ID FTX1207A3A1

2 Gigabit Ethernet interfaces

2 Serial(sync/async) interfaces

1 Virtual Private Network (VPN) Module

DRAM configuration is 64 bits wide with parity enabled.

239K bytes of non-volatile configuration memory.

125440K bytes of ATA CompactFlash (Read/Write)

System image file is "flash:c2800nm-advipservicesk9-mz.124-18.BIN"

Community Member

Re: dte signal on serial interface

you are getting v24 and your x21(v11) pins mixed up.

pin 20 is for v24

pin 3 and 10 are control or as Cisco improperly says DTR for x21/v11

http://www.connectworld.net/x21.html

guves you the pin uses.

Community Member

Re: dte signal on serial interface

Sorry we mixed up the routers.

The correct interface is:

Interface Serial0/1

Hardware is PowerQUICC MPC860

DCE V.24 (RS-232), clock rate 19200

idb at 0x82A6E298, driver data structure at 0x82A7602C

SCC Registers:

Do you have any further ideas?

Community Member

Re: dte signal on serial interface

hi folks,

i've tried it with a V.24 DCE Cable on a WIC-2T and on a WIC-1T. With both configurations i'm not able to enter the "ignore dtr" command. The only reference i've found is that the "ignore dtr" command is supported on a NM-16A/S module. (http://www.cisco.com/en/US/docs/ios/12_4/interface/configuration/guide/hnm16as.html)

Does anybody know if there is a solution to enter the command on a WIC-2T?

Community Member

Re: dte signal on serial interface

I am unsure why you are trying ignore DTR on the router, the router is supplying DTR , likewise the other device needs to supply DTR or it needs to be strapped to another pin and marked high, do a search on the v24 handshake to understand it more.

When you use a DCE cable to the cable suplies DCE hugh to the router,

do a show interface of the router with the dcs cable.

Community Member

Re: dte signal on serial interface

the thing is, that i have a self-made cable between the routers v24 dce-cable and the cashing machine.

in this self made cable i have no pin 20 which is wired.

i have this szenario over 300 times, and it would be very comfortable if i could disable that the router waits for dtr from the enddevice.

of course we could open the 300 self made cables and strap to another pin - but that is a lot of work -

With DTR Pin (20) connected:

Router#sh int ser 0/0

Serial0/0 is up, line protocol is up

Hardware is PowerQUICC Serial

MTU 1500 bytes, BW 9 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation X25, loopback not set

X.25 DCE, version 1984, address ,

RESTARTs 2/0 CALLs 0+0/0+0/0+0 DIAGs 0/0

LAPB DCE, state CONNECT, modulo 8, k 7, N1 12056, N2 20

T1 3000, T2 0, interface outage (partial T3) 0, T4 0

VS 1, VR 1, tx NR 1, Remote VR 1, IFRAMEs 3/4 RNRs 0/0 REJs 0/0 SABM/Es 0/2 FRMRs 0/0 DISCs 0/0

Last input never, output 00:00:13, output hang never

30 second input rate 0 bits/sec, 0 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

9 packets input, 51 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 buffers swapped out

2 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up

Router#sh controller

Interface Serial0/0

Hardware is PowerQUICC MPC860

DCE V.24 (RS-232), clock rate 19200

idb at 0x824450CC, driver data structure at 0x8244C7F0

SCC Registers:

Without DTR Pin (20) connected:

Router#sh int ser 0/0

Serial0/0 is down, line protocol is down

Hardware is PowerQUICC Serial

MTU 1500 bytes, BW 9 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation X25, loopback not set

X.25 DCE, version 1984, address , state R/Inactive, modulo 8, timer 0

Defaults: idle VC timeout 0

cisco encapsulation

input/output window sizes 2/2, packet sizes 128/128

Timers: T10 60, T11 180, T12 60, T13 60

Channels: Incoming-only 1-1, Two-way 2-2, Outgoing-only none

RESTARTs 2/0 CALLs 0+0/0+0/0+0 DIAGs 0/0

LAPB DCE, state DISCONNECT, modulo 8, k 7, N1 12056, N2 20

T1 3000, T2 0, interface outage (partial T3) 0, T4 0

VS 0, VR 0, tx NR 0, Remote VR 0, Retransmissions 0

Queues: U/S frames 0, I frames 0, unack. 0, reTx 0

IFRAMEs 3/4 RNRs 0/0 REJs 0/0 SABM/Es 0/2 FRMRs 0/0 DISCs 0/0

Last input never, output 00:09:23, output hang never

Last clearing of "show interface" counters 00:11:07

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 0 bits/sec, 0 packets/sec

30 second output rate 0 bits/sec, 0 packets/sec

9 packets input, 51 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

9 packets output, 33 bytes, 0 underruns

0 output errors, 0 collisions, 11 interface resets

0 unknown protocol drops

0 output buffer failures, 0 output buffers swapped out

3 carrier transitions

DCD=up DSR=up DTR=down RTS=up CTS=up

Router#sh controller

Interface Serial0/0

Hardware is PowerQUICC MPC860

DCE V.24 (RS-232), clock rate 19200

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