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Fit a printer to a vintage Varian Spectraa 10 plus Atomic absorption spectrophotometer

Varian_chemist

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Sep 23, 2023
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Hello!

I operate a survivor chemical analysis apparatus: a Spectraa 10 +. It was on the market for the first time in 1984. Works fine and gives accurate results. After research, I try to fit a printer with it, the original one was gone. In the manual, they indicate to use a Epson RX-80, LX-80 or MX-80. So I bought a Epson LX-350, same pinter data language ESC/P. Printer works fine, but the Spectraa only detect if the printer is online (E 81 printer offline or not connected) or when I try to print : E 82 printer out of paper. So unable to print chemical results. I use a female to female DB25 adaptator, DB 25 on the Spectraa is male and cable too, and a DB-25 to Centronics connector (CN 36) to connect to the printer. I try two sets of adaptor/cable same result. I try to use a DB 25 serial cable at both end: Spectraa doesn't detect the printer (E 81). If someone have some ideas to solve the problem, they are welcome.

see this youtube video about Spectraa by Varian: Varian Spectraa with Max Gillies. 1984

WIN_20230607_15_46_52_Pro.jpg
 

keenerb

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You might have luck with a retroprinter device from retroprinter.com, I picked one up recently and have been very happy with it. The author may be able to work around your issue if it occurs on that device. I also have an LX350 and have had no issues with my various MSDOS printing escapades so far.

Is it possible there's a problem with the actual printer port on the device? You said the port on the back of the device is MALE, are you certain it's not a SERIAL printer?
 

thunter0512

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I would carefully compare the parallel port pin-out of the original printers (Epson RX-80, LX-80 and MX-80) with the new Epson LX-350.
Likely there is a subtle difference which can be compensated for with a custom cable.
It is quite possible that the Spectraa 10 + needs a signal indicating "ready" before it can print and that signal is mismatched to what the LC-350 generates versus what the analyser expects.
 

Chuck(G)

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Also, make sure that you're using a "straight through" 25 conductor cable that connects all pins if this is a parallel printer port. Some serial cables skimp on the wires.
 

Varian_chemist

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Thank you for your help.

I talk to a technician from Agilent technologies (formely Varian). It tells me that the baud rate is maybe 300 and also that the printer was set in serial mode. As I do some research, you can add interface card to the RX-80. As keenerb write: "You said the port on the back of the device is MALE, are you certain it's not a SERIAL printer?" All Centronics cables are DB-25 male to CN36 male so I guess that is a serial DB-25 cable male/female that was intended for carrying signal. Some documentation talks about Centronics cable. The DS-15 from Varian was discuss in this topic: Varian DS-15.
 

keenerb

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Thank you for your help.

I talk to a technician from Agilent technologies (formely Varian). It tells me that the baud rate is maybe 300 and also that the printer was set in serial mode. As I do some research, you can add interface card to the RX-80. As keenerb write: "You said the port on the back of the device is MALE, are you certain it's not a SERIAL printer?" All Centronics cables are DB-25 male to CN36 male so I guess that is a serial DB-25 cable male/female that was intended for carrying signal. Some documentation talks about Centronics cable. The DS-15 from Varian was discuss in this topic: Varian DS-15.
That's convvenient, the LX-350 has serial support. It's honestly the best retro printer I've found!
 

thunter0512

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Thank you for your help.

I talk to a technician from Agilent technologies (formely Varian). It tells me that the baud rate is maybe 300 and also that the printer was set in serial mode. As I do some research, you can add interface card to the RX-80. As keenerb write: "You said the port on the back of the device is MALE, are you certain it's not a SERIAL printer?" All Centronics cables are DB-25 male to CN36 male so I guess that is a serial DB-25 cable male/female that was intended for carrying signal. Some documentation talks about Centronics cable. The DS-15 from Varian was discuss in this topic: Varian DS-15.
I am surprised that the printer interface is serial. Also 300 bps is very slow. Parallel (Centronics) interface was much more common with these printers.
 

durgadas311

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Using lower BAUD is a simple way to avoid handshaking. If it meant they did not have to implement XON-XOFF in their printer driver, it might have been worthwhile. If the (original) printer could only print at 30 characters per second (including CR/LF overhead), then running 300 BAUD doesn't really hurt anything. It's only when printers got large buffers and faster printing mechanisms that higher transfer rates became beneficial. Although, my experience was that 1200 BAUD was usually "good enough" for avoiding handshake with (most) printers.
 

atariquest

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My first IT job out of college was working in a hospital. One of the things I had to do often was interface labratory equipement via serial to printers, computers, other equiment, and the TCP/IP network. Back then I wrote my own serial "sniffer" in Tcl/Tk to diagnos issues and figure out things like cabling requirements, baud rates, etc.

My suggestion when working with serial connections is to start with software to figure out how to connect and configure hardware. If you use Windows, I suggest trying Tera Term. You can setup a serial connection, play with the baud rate, parity, stop bits, handshaking, etc until you find a combination that works. You should be able to see the serial stream from the instrument in the terminal. Some of it may look like garbage i the prit stream contains a bunch of printer specific control codes, but you will at last know if the instrument is able to communicate.

Of course, you need to make sure you have the correct cabling between the instrument and the computer or printer. RS-232 has the concept of DTE (Data Terminal Equipment) and DCE (Data Communications Equipment). The idea is that you can connect a DTE device directly to a DCE device with a "straigh through" cable. For simplicity lets pertent the cable does not have 25 connectors, but only two, a transmit (Tx) and receive (Rx).
DTE Tx -----------------------------------------------> DCE Rx
DTE Rx <---------------------------------------------- DCE Tx
As you can see a straight connection is made between the DTE device's Tx to the DCE device's Rx and vice versa. All is good!

However, if both devices are DTE or both are DCE you end up with this situation:
DTE Tx -----------------------------------------------> DTE Tx
DTE Rx <----------------------------------------------- DTE Rx
In this case transmit is connected to transmit and receive is connected to recieve. The two devices can not communicate. This is the situation when you need a "cross over" which is also sometimes refered to as a "null modem" cable.
DTE Tx ------------------- \ /---------------------> DTE Tx
DTE Rx <------------------/ \ ----------------------- DTE Rx
This cabling changes the wiring of the Tx so that it is connected to the Rx and vice versa as needed.

If you have an oscilliscope you can figure out if the instrment is DTE or DCE by probing pins 2 and 3. When transmitting data from the instument you will see the voltage rise and fall within the range of +-3 to +-15 volts. Most older devices are typically around +-12 volts while newer are typically +-5 volts or less. If the transmission is on pin 2 it is DCE, pin 3 is DTE. Your PC is DTE. Analizing the serial stream will also reveal the stop bits, parity, and baud.

Marvin
 

cruff

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Or just get one of those indicator blocks. ...
I second this, I have one from the 90s that has been useful on a number of occasions. Of course if you need another piece of vintage equipment HP made a nice serial protocol analyzer series starting with the HP 4951A.
 

Varian_chemist

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The LX-350 works well with a Windows Vista laptop with the intallation CD-ROM provided with the printer. I try everything with the printer setting. The null modem cable option seems to me to be a good option to solve the problem. I've made some search on the web and I can confirm that the printer is connected parallel. See on these pictures: varian_spectraa-20_3246100.jpgvarian_spectraa-20_32461000.jpg
 

atariquest

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Now that you know for sure it is parallel / Centronics that cabling is straight forward (DB-25 to centronics).
https://www.amazon.com/C2G-02798-Centronics-Parallel-Printer/dp/B00005114K

I noticed in your newest photos the use of a Citizen branded printer. That printer emulates the Epson FX series commands, so that is consistent with your initial post regarding printer compatibility.

I took a quick look at the LX-350 manual. Your printer has parallel, serial, and USB ports. The manual states that the printer has three interface modes (auto, parallel, serial, USB). You might want to check that setting to make sure it is switched to parallel and see if that makes a difference.

Marvin
 

Varian_chemist

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Sep 23, 2023
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I would carefully compare the parallel port pin-out of the original printers (Epson RX-80, LX-80 and MX-80) with the new Epson LX-350.
Likely there is a subtle difference which can be compensated for with a custom cable.
It is quite possible that the Spectraa 10 + needs a signal indicating "ready" before it can print and that signal is mismatched to what the LC-350 generates versus what the analyser expects.
Exactly, I use another system disk, one to print edited analysis report. Disk that was stored in the computer department. I get a message: "printer is not ready". So yes the Spectraa 10+ needs a ready signal to print.
 

thunter0512

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Now that you know for sure it is parallel / Centronics that cabling is straight forward (DB-25 to centronics).
https://www.amazon.com/C2G-02798-Centronics-Parallel-Printer/dp/B00005114K

I noticed in your newest photos the use of a Citizen branded printer. That printer emulates the Epson FX series commands, so that is consistent with your initial post regarding printer compatibility.

I took a quick look at the LX-350 manual. Your printer has parallel, serial, and USB ports. The manual states that the printer has three interface modes (auto, parallel, serial, USB). You might want to check that setting to make sure it is switched to parallel and see if that makes a difference.

Marvin
I just checked the LX-350 manuals (quick setup and user manual), but did not see any configuration switch or similar to select among the 3 supported interface modes (USB, serial and parallel). I assume this means it auto-detects the interface.
 

Varian_chemist

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I just checked the LX-350 manuals (quick setup and user manual), but did not see any configuration switch or similar to select among the 3 supported interface modes (USB, serial and parallel). I assume this means it auto-detects the interface.
There is a setting mode with many item and one to choose between Auto, Parallel, Serial, or USB. Auto can detect which interface is connected. I was thinking about auto line feed, maybe if I try it on? Otherwise, I found a document explaining that a software made to control the spectrophotometer use an Epson printer which is centronics compatible.
 
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