HP 50g Connection to Multimeter
in [HP48]
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From: obr04 on 9 Dec 2007 00:20 I am trying to connect my HP 50g to a multimeter (MAS345) with a baud rate of 600. I found a small program in Google Groups that allows you to lower your baud rate below 2400 (the lowest range in the 50g). Unfortunately I have not been able to establish a connection to the millimeter. I am not sure if it is due to the "baud modifying program" or due to another issue. I have been able to connect to my computer with both devices (the 50g and the multimeter) at 600 baud. The multimeter's specs indicate that it sends data at 600,n,7,2. To send ASCII to the multimeter (any character should initiate feedback per the multimeter manufacturer) I am using the XMIT command (it returns a 1 in stack-1 which is good), and to receive information I use the SRECV command (it returns a "" 0 in stack-1 which is not good). It appears that no items are stored in the buffer, which may indicate that the IO-parameters may not be matching and nothing is being received. Does any one know of other means or 50g commands that can work to troubleshoot this issue? Regards, Bryan
From: TW on 9 Dec 2007 00:28 On Dec 8, 10:20 pm, ob...(a)yahoo.com wrote: > I am trying to connect my HP 50g to a multimeter (MAS345) with a baud > rate of 600. I found a small program in Google Groups that allows you > to lower your baud rate below 2400 (the lowest range in the 50g). > Unfortunately I have not been able to establish a connection to the > millimeter. I am not sure if it is due to the "baud modifying program" > or due to another issue. I know it will connect at ranges like that no issue. It does work properly. > I have been able to connect to my computer with both devices (the 50g > and the multimeter) at 600 baud. The multimeter's specs indicate that > it sends data at 600,n,7,2. I suspect the 2 might be the issue. I am correctly interpreting that as 2 stop bits? If so, I don't think the calculator can handle it as it only does 1 stop bit. Am I wrong on this anyone? > I use the SRECV command (it returns a "" 0 in stack-1 which is not > good). What is your STIME value? If it is extremely short it might be timing out. TW
From: obr04 on 9 Dec 2007 00:36 On Dec 8, 9:28�pm, TW <timwess...(a)gmail.com> wrote: > On Dec 8, 10:20 pm, ob...(a)yahoo.com wrote: > > > I am trying to connect my HP 50g to a multimeter (MAS345) with a baud > > rate of 600. I found a small program in Google Groups that allows you > > to lower your baud rate below 2400 (the lowest range in the 50g). > > Unfortunately I have not been able to establish a connection to the > > millimeter. I am not sure if it is due to the "baud modifying program" > > or due to another issue. > > I know it will connect at ranges like that no issue. �It does work > properly. > > > I have been able to connect to my computer with both devices (the 50g > > and the multimeter) at 600 baud. The multimeter's specs indicate that > > it sends data at 600,n,7,2. > > I suspect the 2 might be the issue. �I am correctly interpreting that > as 2 stop bits? �If so, I don't think the calculator can handle it as > it only does 1 stop bit. �Am I wrong on this anyone? > > > I use the SRECV command (it returns a "" 0 in stack-1 which is not > > good). > > What is your STIME value? �If it is extremely short it might be timing > out. > > TW I tried setting STIME to 10-sec, but it still did not work.
From: obr04 on 9 Dec 2007 01:08 On Dec 8, 9:36 pm, ob...(a)yahoo.com wrote: > On Dec 8, 9:28�pm, TW <timwess...(a)gmail.com> wrote: > > > > > > > On Dec 8, 10:20 pm, ob...(a)yahoo.com wrote: > > > > I am trying to connect my HP 50g to a multimeter (MAS345) with a baud > > > rate of 600. I found a small program in Google Groups that allows you > > > to lower your baud rate below 2400 (the lowest range in the 50g). > > > Unfortunately I have not been able to establish a connection to the > > > millimeter. I am not sure if it is due to the "baud modifying program" > > > or due to another issue. > > > I know it will connect at ranges like that no issue. �It does work > > properly. > > > > I have been able to connect to my computer with both devices (the 50g > > > and the multimeter) at 600 baud. The multimeter's specs indicate that > > > it sends data at 600,n,7,2. > > > I suspect the 2 might be the issue. �I am correctly interpreting that > > as 2 stop bits? �If so, I don't think the calculator can handle it as > > it only does 1 stop bit. �Am I wrong on this anyone? > > > > I use the SRECV command (it returns a "" 0 in stack-1 which is not > > > good). > > > What is your STIME value? �If it is extremely short it might be timing > > out. > > > TW > > I tried setting STIME to 10-sec, but it still did not work.- Hide quoted text - > > - Show quoted text - The multimeter protocol indicates the following: Baud rate : 600bps No parity check 7 bits ASCII code 2 stop bits I had my computer set to these parameters when I connected each device to it, both worked. Independantly however, independantly having the 50g connect to another device may not be so easy. Is there any way to change the stop bits in the 50g?
From: obr04 on 19 Dec 2007 23:11
On Dec 11, 7:11 pm, "James M. Prange" <jmpra...(a)i-is.com> wrote: > ob...(a)yahoo.com wrote: > > After further testing the DB-9 for themultimeterI found out that > > pins 2, 3, 5 and pin 7 are connected. This would indicate that > > possibly pins 2 and 3 are Tx/Rx, pin 5 is probably GND and 7 ??? Could > > this be the power line? > > As noted before, yourmultimeterseems to be a DCE device, since, > if I understand correctly, it can communicate with the PC without > using a null modem > > With a DE-9 (usually incorrectly called DB-9) connector, normally, > pin 2 would be the data signal from DCE to DTE, pin 3 would be the > data signal from DTE to DCE, pin 5 would be the signal ground, and > pin 7 would be the request to send signal from DTE to DCE. > > Request to send is normally a hardware flow control signal, but if > this hardware flow control were actually being used, one would > expect a connection to pin 8, the clear to send signal from DCE to > DTE. If there's no connection to pin 8, then it appears to me that > yourmultimetermay well indeed be expecting to use a request to > send signal on pin 7 as a power source for its RS-232 > level-shifter circuits. > > > If so, do you know any way to provide power perhaps through a > > commercial adapter between the two DB-9 plugs? > > Assuming that you're using the hpcalc.org adapter (which is > configured as a DTE device) with your50g, I'd try making a "power > adapter" cable (or use a double-ended shell) with male and female > DE-9 connectors with pins 2, 3, and 5 connected straight through, > plus a power source (5VDC-15VDC; an ordinary 9V battery should > suffice) connected between pin 5 (signal ground) and pin 7 > (request to send) of the male connector (no need to connect pin 7 > of the female connector). The polarity of the power source > shouldn't matter, but I suppose that it just might, so if one > polarity doesn't work, then try the other. I expect that an AC > power source should also work, but in that case, the *peak* > voltage (not the RMS voltage) should be not exceed 15V. At worst, > if themultimeterreally is using request to send as a hardware > flow control signal instead of just a power source, then this will > force it either on or off, without doing any hardware damage to > yourmultimeter. > > Now that I think of it, just in case yourmultimeteris using > request to send as a hardware flow control signal instead of (or > in addition to) a power source, it would probably be better to > connect the power source positive to pin 5 (signal ground), and > negative to pin 7 (request to send), so that it doesn't "think" > that the calculator wants to send something. > > If you want to use your Samson Cables adapter (which is configured > as a DCE device) instead, use a pair of female connectors, with > each connector's pin 2 connected with the other's pin 3, pins 5 > and 7 connected straight through, and the power source between > pins 7 and 5, thus making a combination of a "power adapter" and a > null modem in the same adapter. It won't matter which end is > connected to the Samson Cables adapter and which to the mutimeter. > Alternatively, use a male-to-male null modem adapter or cable > between the Samson Cables adapter and a home-made power adapter as > built for the hpcalc.org adapter. > > -- > Regards, > James Thank you for your help. I am afraid however, that the addition of a power source to pin 7 did not help either. I have to do more research on these types of connectors. Unfortunately I have not been able to gather information on the RS232 diagram for this MAS345 Multimeter, but I will continue searching. I will let you know if I ever get it to work with the 50g. |