Kramer VP23N Got control but no feedback from switcher

mncchartier

Working on a room that has a Kramer VP23N switcher. I am able to switch inputs and outputs properly on it but I am not getting any responses back from the switcher. I tested the cable by using it with the Kramer software and also just did a firmware upgrade on the switcher using that cable. I get feedback with their software.

nDebug is set, the data event is just testing to see how I need to handle the feedback. I am mainly looking to see what will be in the buffer so I can do my parsing.

DEFINE_EVENT
DATA_EVENT[dvDEV]
{
    ONLINE:
    {
	SEND_COMMAND dvDEV, 'SET BAUD 9600,8,N,1'
	
	CLEAR_BUFFER cBUFFER
    }
    STRING:
    {
	cBUFFER = "cBUFFER, DATA.TEXT"
	IF (nDebug) {SEND_STRING 0, "'VP23C COMM cBuffer ', cBUFFER"}
	WHILE (FIND_STRING (cBUFFER,"13",1))
	{
	    DISPMSG = REMOVE_STRING(DATA.TEXT, "13", 1)
	    SELECT
	    {
		ACTIVE(FIND_STRING(DISPMSG, '00',1)):
		{
		    OFF[nWaiting]
		}
	    }
	}
    }
}

Hedberg

Is it a commercially purchased cable or is there a null adapter connected to the AMX port? If so, try with just three wires and the null adapter connected to the Kramer end rather than the AMX end.

HARMAN_Chris

mncchartier,
The reason for Hedberg's cable question is because your PC serial port is 232 all the time, but the AMX NI serial port is multi-function and can do 232/422/485. If the NI Master senses voltage on certain pins, it will switch modes and that changes the receive pin.

AMX.com shows the cable for the VP23 (not the N, but they are probably the same) as being 2,3,5 cross-over:

http://amx.com/inconcert/Cbl/CableViewingFrame.asp?CblNo=1189&lk=4783EF75-BED4-4846-A331-F8FBAE26

Can you confirm that these are the only pins in your cable?

mncchartier

Thank you. I made up a new cable with only the 3 wires and no null modem and it is working. Thanks

Hedberg

AMX_Chris wrote: »

mncchartier,
The reason for Hedberg's cable question is because your PC serial port is 232 all the time, but the AMX NI serial port is multi-function and can do 232/422/485. If the NI Master senses voltage on certain pins, it will switch modes and that changes the receive pin.

AMX.com shows the cable for the VP23 (not the N, but they are probably the same) as being 2,3,5 cross-over:

http://amx.com/inconcert/Cbl/CableViewingFrame.asp?CblNo=1189&lk=4783EF75-BED4-4846-A331-F8FBAE26

Can you confirm that these are the only pins in your cable?

I think it's actually a bit simpler than that. The serial ports may either be 232/422 or 485 and that is controllable. When configured for 232/422 they are set to communicate via either protocol. There is no switching between RS232 and 422, the two different protocols are handled by using different pins:2,3,5,7,8 for RS232 and 1,4,6,9 for RS422. The master neither monitors no cares whether the communication is RS232 or RS422 -- it will work with either without doing anything.

Now, if you look at the wikipedia entry for "null modem," you'll see that a null modem cable may flip 6 and 4 and may short pin 1 to pin 6 at each end. This, as I understand it, screws up the RS422 transmit and receive in such a way that the port will transmit but won't receive.

I've seen this cause problems with those little bitty null modem adapters that come with Polycom codecs if attached to the AMX DB9 port but they work fine if using three wires when connected to the Polycom DB9. Also, 9 wire cables seem to work OK if there is no adapter, but will sometimes be snafu with an adapter at either end. Of course, a three wire (or five, if necessary) properly wired (either straight or cross-over) cable is the way to go.

annuello

We've also had several (5 out of 200?) of the Kramer-supplied crossover adaptors be faulty from day 1. I opened up one of the snap-together-shell type and discovered a conductor floating freely rather than being soldered properly to the D9. It went straight to the bin, along with the other questionable adaptors. I can't vouch for the pre-moulded type since it was better use of time/resources to simply make out own 2,3,5 crossover cable than to diagnose the failure rate.

Roger McLean
Swinburne University

Darkside

annuello wrote: »

We've also had several (5 out of 200?) of the Kramer-supplied crossover adaptors be faulty from day 1. I opened up one of the snap-together-shell type and discovered a conductor floating freely rather than being soldered properly to the D9. It went straight to the bin, along with the other questionable adaptors. I can't vouch for the pre-moulded type since it was better use of time/resources to simply make out own 2,3,5 crossover cable than to diagnose the failure rate.

Roger McLean
Swinburne University

+1

Other rationales to not use an adaptor for a cable :
- less joins reduces your point of failure risk
- a custom made 235 cable can be made to length (nice in the rack) and usually only takes 10minutes to make!