I got a RT-200 gas flow analyzer,test function is normal.
I want to know if any individual or organization is using it now?If you are still using, please contact me, send an email or post


I disassembled it,and backup 6 EEPROM programs,if there is a failure in the future, please use it for future maintenance,at the same time, I will upload the backup and share it with friends who need it


I see that the microcontroller on the motherboard has been polished,if you know the model number please let me know
By observing the motherboard, I found that it has RS-232 function,I guess it may be used for calibration,you can contact me if you are interested

I hope to increase the functionality of this machine through my own efforts
If you are interested or related questions, you can contact me, thank you

Below is the part of the motherboard I disassembled

Pressure module and flow module

As you know, I am (or at least, used to be) somewhat of an RT-200 aficionado myself (back in the day - late 1980's - some of us used to envy biomeds who had access to this fine piece of test equipment). But perhaps it may help if you gave us an idea about what you are trying to achieve here.

The RS-232 interface was an optional extra. Where installed, the connector to the outside world would occupy slot J-1 as shown at top left of the second image at post #76167 (see also the image posted below).

Slot J-2 was for the IEEE-488 interface connector. The General Purpose Interface Bus (GPIB - originally from Hewlett-Packard) is apparently still often found on test equipment of the "bench" type. I have never seen an RT-200 with GPIB myself. I haven't been able to find an image of an RT-200 with GPIB on line, either.

It would be nice if you could bring these interfaces back to life; as well as - who knows - adding new ones (eg, USB). Apparently, GPIB to USB adaptors are available these days. As well as:- clue.

One of the things I liked about the RT-200 are the opportunities it appeared to offer for expansion. As you know, there are a number of empty connectors on the main board. In this regard I am reminded of 8-bit computers from the same era (especially the BBC Model B and (or) Master). Who knows what use they could be put to!

The design of the RT-200 suggests a "stack", and I have often wondered if Timeter planned more modules. Its predecessor, the RT-100, included a voltmeter and electrical safety tester, and I imagine that the RT-200 could have offered those within another module (I had, at one time, toyed with the idea of adding my own). It would have been nice also to have a module that could handle fluids (for testing infusion pumps etc.). The extra bus connector (see the ribbon cable at top left of the bottom image - the Flow module - at #76169) seems to suggest such possibilities.

As we have found, one of the problems with keeping the RT-200 going (as well as, perhaps, enhancing its capabilities) is a lack of detailed technical information. Connector pin-outs, chip numbers etc. As you have already indicated, this equipment stems from a time when chips were often rendered anonymous! I'm guessing, too, that some of those chips (MCUs) may now be hard to find, and their function may therefore need to be "re-created" in some imaginative way. No doubt you can look forward to many hours of fun!

Lastly, I have yet to hound down any information regarding the DIP switches (S1-S8) on the main board. The manual simply mentions "Programming Switches" (S1-S6 appear to be ON, S7-S8 OFF).

Knowing of your interest, this morning I got in touch with the guy to whom I donated my own RT-200 six years ago. It was a nice clean example (but no J-1, or J-2 interfaces, alas). I was wondering if it was still unused, so maybe I could retrieve it, and then possibly answer some of your questions. Apparently he uses it in some sort of project where he has a need to measure water flow (hopefully, he uses some kind of liquid-to-air adaptor). At least, then, it has gone to a good home!

According to what you mean, I tried to mark the signal points in the figure below. Is this a connection?

About J2，GPIB signal interface I found GND and RX/TX signals,is connected to U9,but this signal definition looks like the definition of RS232 signal,Other signals, such as 8000, A000, B000, 6000 I am still looking for
About J1，Under normal conditions，Short circuit socket,i check 3 wires,but GND was not found,Because based on experience,if it is RS232 signal，at least one wire is directly connected to GND.I do not know why it has to be like this.J2 I'm still looking for a signal,may take time

I cleaned the dust inside the host yesterday,Check various functions after booting,basically normal.
In the next few days,I will try to recalibrate it,Including voltage calibration, pressure calibration, flow calibration...
I will follow the progress steps,update content,take a good note,Share with friends who are still using it
If you have experience in maintenance and use, welcome to share

Rather confusingly, J1 on the main board does not connect to the J-1 ("RS232C") on the back of the unit. Similarly for J2 and J-2 ("GPIB IEEE-488").

In fact J1 on the main board acts as a switch to select EPROM U1 to act as either RAM or ROM.

I'm not sure what J2 on the main board is for, but GPIB (IEEE-488) should have 24 pins.

Looking at your images of the main board, I am undecided whether J3 ("Aux Interface") and J4 ("Interface") or J5 ("Expansion No.2)" and J6 (Expansion No.1") are the ones to dig into for RS-232 and GPIB. I'm guessing J3 and J4.

But it would be nice to get GPIB going, as (presumably) you could then control your RT-200 remotely using the SCPI "language" (Standard Commands for Programmable Instruments; usually pronounced "skippy").

By the way, I notice that chip numbers are still visible on many of the (smaller) chips, but I cannot quite make them out. If you could list them for us, that would be nice. For instance, U8 and U14 adjacent to J2 should give clues to what J2 is meant for.

By checking the motherboard,i found that RS232-C should be connected to J2.I haven't figured it out yet,J2(8000), (A000), (B000)74LS154N output,modern general RS232 three-wire control communication,But it has 7 wires or more
Because I don’t know the U9 model，74LS154N is controlled by U9,Progress blocked,If anyone knows, please tell me the model,I will continue to travel

J1 is only used for reading or writing, only as a switch,Control EPROM writing program or prohibit writing.

GPIB interface,I guess there should be a small board,it connects to J3、J4、J5、J6,input Output,control the machine remotely through the program

I check the pressure module and the flow sensor module,found that the sensor could not find the model,If you know please let me know.I am worried about damage to the equipment,I will back up the pressure and flow sensor test data,Support future damage。scilicet。I will save the pressure value or voltage value corresponding to the flow value.
If you have better suggestions please let me know



Clear picturehttps://ftp.bmp.ovh/imgs/2021/03/0565ee3aa1699c17.jpg
https://ftp.bmp.ovh/imgs/2021/03/233585f3aea6e578.jpg

It looks like you've been very busy!

I notice a couple of intriguing wire links on the underside of the main board.

Re: sensors (and chip numbers); yes, it seems that Timeter were very keen to guard their secrets.

I am also suspecting that a daughter board formed part of the GPIB "package".

On the face of it I disagree with you about J2 being for RS-232, although I don't have the time for any more "research" just now - except to mention that the Signetics 74LS154 (U8) is (was) a "1-of-16" Decoder/Multiplexer (datasheets are available on line).

I have been studying hard I updated the 74LS154 circuit.Since I don’t know the U9 model, I can only enter here

... and U14 (above J2) - MM74HC32N - is a Quad 2-Input OR Gate.

I see a few SN74LS374N there on the main board ... these are basically sets of eight clocked flip-flops; typically used for "driving the bus lines in a bus-organized system"!

OK ... here's another random guess:- it seems to me that U8 is tied to the two main expansion connectors (J5 and J6). I'm wondering if it (U8) is a VIA (Versatile Interface Adaptor); mainly as VIA's used to be popular back in the 1980's (again, the BBC Micro comes to mind). It looks like it may be an Intel device (with forty pins). Could it be the Intel 8255, I wonder?

That's enough for now, as I don't want to be dreaming about this stuff (it's midnight here).

Finding signals takes time,I finished part of the work,Please refer to the definition of U9,I found the power supply and negative,The negative pole of Intel 8255 is not pin P8,But I think it should be a similar MCU

The J2 interface is based on my current signal trend,It looks like it is communicating with U9，Read or write EEPROM via U9

At first glance it seems that, in the Intel 82xx series of that era, only the 8255 (Parallel I/O Interface) and 8237 (Direct Memory Access - DMA - Controller) had forty pins.

Another candidate from those days could be the National Semiconductor 8250 UART chip ("one of the most prolific and most cloned UART chips", apparently ... and now lots of stuff on line), which also came in a forty-pin DIL package. Pin 20 is Ground, Pin 40 is +5 VDC.

UART:- Universal Asynchronous Receiver/Transmitter. An integrated circuit for implementing the interface for serial communications (eg, RS-232).

I found a strange phenomenon,If the airflow is from back to front，RT200 cannot display data,is this normal?Or my connection is incorrect?

Which Function Codes are you using there? Try 46 to 48.

See page 5-4 of the May 1988 manual.

Assuming that one of those forty-pin devices must be the microprocessor ... well, the Intel 8088 (also 8080 and 8086) came in a forty-pin DIL package. And, looking at the image of the underside of the main board, once again it looks like U9 has the most connections ... so I'm going for that one as the microprocessor. It is also the one nearest to the EPROMS!

Other chips:-

HD74LS04P (U17, U19):- Hex Inverter (x4)
SN74LS32N (U23):- Quad 2-Input OR Gates
SN74LS153N (U11):- Dual 4-line to 1-line Data Selector/Multiplexer
SN74LS393N (U18):- Dual 4-bit Binary Counter

HN462732G (U1-U6):- 8-bit 32 KB EPROM

Already noted:-

74LS154 (U8):- "1-of-16" Decoder/Multiplexer
MM74HC32N (U14):- Quad 2-Input OR Gate
SN74LS374N (U15, U16, U21, U22):- x8 clocked flip-flops

If it is Intel 8088 series MCU,Looks no error.At least there are currently no conflicts,I searched for the real thing about 8088 and it really looks a lot like it

After finishing the work at hand, I will continue to look for signals,I hope other information can help me confirm whether it is 8088

Today I bought a professional flow meter,It is said to be a maintenance tool for the Dräger anesthesia machine or ventilator.I plan to use it to compare rt200 traffic.

I wonder how clean the sensors (and tubing) are inside the Flow Module. It's best to use a filter on the High Flow inlet port if possible.

Yes, it looks cleaner,I prepared the filter,I am waiting for a high pressure joint.The original connector is missing

Low pressure range data

Nice test equipment.

Mysterious pressure sensor

SenSym is now part of Honeywell ... so I imagine that a modern alternative will be available. For example.

But the model of the old pressure sensor cannot be found,I only see MICRO SWITCH usa and sensym 926 sz75153,

I searched and did not find similar information,If damaged will be a big problem

When preserving the life of old equipment, sometimes we have to substitute, or improvise. In this case, it should not be too difficult to find sensors in the pressure ranges required.

But I suspect that the real problem would be that, if either sensor were to be replaced, the calibration settings (in the corresponding EPROM) would be upset.

Yes, this is the ultimate goal of the voltage test point I am measuring.If you want to replace it with another sensor, you must make the pressure value correspond to the same voltage value.Of course this is the worst case.
If it can be replaced with the same sensor, this is the best solution.
But I must prepare for the worst

I am wondering what sensors the Timeter RespiCal T-300 uses (or used).

I took a clear picture of the sensor

This is a good suggestion,I am looking for all the information about the Timeter RespiCal T-300,But no internal disassembly pictures or detailed repair manuals were found

Indeed; but the RespiCal is likely still to be in common use ... so we can always hope than someone will oblige.

High pressure sensor


Please forgive me, I did not test all gears due to excessive pressure

I did not find more detailed information about T-300,I have read the T-300 user manual，Its structure is similar to RT-200，The display part changes to liquid crystal dot display.
I think the extra cable on the bottom layer of RT-200,It may be connected to the oxygen sensor circuit board.
Because I saw the T-300 added the oxygen concentration test function
Can T-300 allow users to perform calibration and calibration? Through software?
If so, this is a good way

Yes; I suppose we should regard the T-300 as an evolution of the RT-200, especially as it takes the next step into "computer control" (in the Win 95 era). Whether that was actually a good move, is best left as a matter of opinion.

But (for balance, and as you will have seen in the Operation Manual) at least that allows default settings to be held in a computer file (Units.cfg).

Yes; the T-300 has an internal oxygen sensor. Hopefully, it is a common type (galvanic). Perhaps you can add one of these in your next module design!

On that note, my own idea was to poke a laptop hard-drive into one of the RT-200 modules (or add another). Just another pipe-dream, really.

PS: does anyone else remember Mark Colton's PipeDream software? The original PipeDream, that is.

Just got a bad news,I contacted a Honeywell official,Got the following reply

Sadly, all you did there was waste your time.

The Noble Technicians of the Dark Side should not need (nor expect) assistance from Corporate Types!

As previously noted, there will be many (I should imagine) sensors available elsewhere that meet the basic specifications required. Some adaption may be needed, but that is in the nature of such ventures.

The world is full of components of all types, and from all eras. It's "just" a question of hounding down what is needed (or something that will do the job). Often easier said than done, I grant you ... but a lot less effort in these days of the internet. Automotive, aircraft industries as well as medical, electronics and what-have-you. Not as much "fun" as tramping through the souks in sandy places (or the "Godowns" of Hong Kong) every evening, perhaps - but likely to be more productive.

I will continue to do a good job of data backup,Looking forward to not using it
Old equipment seems to have to rely on itself to provide technical support
Do you know what sensor is indicated by the arrow in the figure below?


Temperature sensor probe?

Yes; I'm pretty sure they are Heater and Temperature probes.

How come? Well, they get mentioned here ... which appears to be a patent application for the RT-100 ... and it's a pity that the figure illustrations mentioned are nowhere to be found.

The plot thickens!

Old equipment:- yes, as we know, it is not uncommon for successful "pioneering" companies (such as Timeter, Metron, Bio-Tek et al ... and there are many others) to be bought up by the Big Corporate Players. The support of "legacy" equipment then almost always gets forgotten about, or (at best) left to gently wither on the vine.

For instance ... are we ever likely to see a RespiCal II (T-400) - complete with USB and what-have-you fit for the modern age? Somehow I doubt it.

But the Rigel VenTest 800 (IMT PF-300) looks nice.

This happens in all industries. Take, for example, Saab cars ... "Saab the Innovator" (and they were) becomes "Saab the Cavalier Clone" (or, if you like, the Cadillac BLS) ... and then binned altogether.

I carefully observed this high-speed flow sensor,Inside is a gas resistance made of a lot of copper sheets,I think the rapid flow of gas should be prevented,Lead to pressure difference.Get P+ and P- pressure values,Corresponding to the flow value according to the pressure difference, and then display.
There is a copper tube at the front of the airlock chamber and a copper tube at the rear.Behind the copper tube is the red wire and the blue wire.Leave the circuit.I test the resistance of the red and blue wires separately,They are all 3.93K ohms,Are they temperature sensors PT100? pt1000? Or K galvanic couple

Data backup of flow module,My flow meter can only reach 16.0L/min

I have confirmed the model of the high pressure sensor

I am drawing a schematic diagram and hope to modernize and upgrade the RT-200.
Due to the wear and tear of the U13 model, I am unable to determine the exact model. I have measured the definition of the U13 pin,I see the Intel logo in the appearance, and there is an i XX53 Intel 80 mark on the chip

Added VCC and GND definitions for U12 and U9

schematic diagram

About "zeroing" and "drift" ... Section F of the March 1988 manual talks about this.

Meanwhile the Troubleshooting Section informs that "excessive drift" shall generate a "HELP 0" display; so if no such message is evident, hopefully we can assume that all is well. There are, however, some pots that may be tweaked if you insist!

Unfortunately, my RT-200 RT-203 flow module is faulty.
The fault phenomenon is that the screen displays "HELP 0".Press "30" to enter the V/F converter and see that the data is continuously decreasing.Use a digital multimeter to measure A3A3A1 (HI, LO voltage values),It is a constantly changing value, not 0 +/-.005VDC.

I tried adjusting A3A3A2 R1102?Try to keep the V/F converter in the range of (250-500),HI-LO voltage maintained at 0 +/-.005VDC?

But after restarting, it immediately displays "HELP 0",The V/F converter shows a value of about 710 and keeps decreasing.Only when the V/F converter display value is in the range of (250-500) ,After entering the function code, it can be displayed normally and "reset to zero" normally.But this state won't last long,When the V/F converter is lower than 250, "HELP 0" appears again


I removed the pressure sensor from the RT-203 module PCB,Use 4 4K ohm fixed resistors to form a Wheatstone bridge,Reconnect the sensor socket,The V/F converter display value is stable, and the HI-LO value is also stable.

Final pressure sensor thermal stability failure, possibly due to aging.

If anyone knows a compatible sensor model or the data sheet of the original sensor, And the calibration method after replacing the pressure sensor?please let me know. I would be very grateful.Thanks










test video

In the process, I discovered a mysterious resistor network "1698-99-0"

I drew the circuit schematic.
If anyone can understand it,And know the meaning of R1109 (TC), R1102 (NULL), R1104 (XD BAL), R1116 (ZERO), R1123 (VB SET), please tell me,Thanks.

Hallo everyone.
I found the model number of this pressure sensor, it is "125PC05D1", and found the data sheet, unfortunately it has been discontinued and I have not yet found a replacement model for it

Hello, here is offer at ebay

https://www.ebay.com/itm/153522618703

Thanks.

I understand, but I am in a country where I cannot buy from EBAY or the shipping cost is much higher than the price of the pressure sensor itself.
So I can only look for another model to replace it.

I recently obtained some information about the RT-200 RS232-C communication interface converter board, and I'm sharing it here for anyone who might be interested.
There is no clue yet about the software that matches the RS232-C communication board. If anyone has a matching online software, please feel free to contact me. Thank you

Do you have the instrument in your possession? The RS-232 format should be well known. If you have access to the RT-200, what are you getting as output(s) on J1?

I notice that J-2 remains blank. I'm surprised that the interface board only supports J-1 (the RS-232 connector); which is a pity as there is a lot of info on the GPIB (General Purpose Interface Bus) on line. I believe that the GPIB is a parallel format.

The picture was taken by a Canadian seller on eBay; only his RT-200 main unit has an RS-232C interface on the back.(https://www.ebay.com/itm/1879982158...338722076&customid=&toolid=10050)
This is the only RT-200 host I can currently find with an RS-232C interface output.So I had him take pictures of the internal motherboard.
The markings on the chips on his RT-200 motherboard were intact and had not been erased.


My own RT-200 main unit doesn't have this kind of signal adapter board, meaning J3 and J4 are empty, and expansion ports NO1 and NO2 are also empty.

It seems that some software is needed to interface with the J-1 port, but I haven't found any information or clues related to that software.(It looks like a printer interface, meaning it can only output signals.)
Frankly, I have never seen an RT-200 mainframe with a GPIB interface.

I've been looking for how Timeter calibrates the RT-200.Because the U1-U6 EEPROM chips on the RT-200 motherboard are UV-erasable EEPROM chips.In other words, it is read-only and the data cannot be modified in real time.?Unless they test it once, then remove the chip, erase the data, rewrite the new data, and then reinstall and test it again.?

I'm hoping that someone somewhere shall be able to provide "chapter and verse" on the GPIB of the RT-200. Surely GPIB must have been used as it lends itself more usefully to instruments such as the RT-200 ... that is, for data logging purposes.

I'm guessing that RS-232 would be more useful when recording varying output values. But I am wondering if the RS-232 facility could also be for inputs to control the RT-200 ... remotely, for example. I'm wondering also if both interfaces ever appeared on a RT-200 (and could this indeed even have been possible .. seeing as how close together the J3 and J4 connectors are).

I notice from your images the DIP switch on the serial comms board (as would be expected for setting up protocols) and also that the board is plugged in at J4 on the main board. Perhaps J3 is for the GPIB.

I have been unable to find any information regarding either interface. But someone must know.

Lastly, need I remind you that the old (May 1988) RT-200 manual makes clear that U1-U6 ... "Do not remove EPROMs unless instructed by factory"! Notice also that (in the images you have provided) the EPROMs are marked by hand with the instrument serial number.

This is a clear picture of the interface circuit;

it appears that it requires computer software to function.