Technical note - input and output modes for Amplicon panels

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Input specifications


Inputs operate in "low voltage" mode (-5V to +1.5V low, +4V to +12V high) or "high voltage" mode (-15V to +2V low, +10V to +30V high), with or without optoisolation, chosen for each input individually. Optoisolation is recommended, and the voltages quoted are for the optoisolated mode.


The Amplicon EX230 input card


SK5 is a 'user' connector block with 6 connections on it. It is connected via the 37-way ribbon cables to the equivalent block on the EX233 card. This is handy for providing external power and data lines that are shared between all cards. SK6 provides power and ground to the board itself (and is usually not needed as the 37-way connector provides power; see notes for J1-J6 below). SK7 is the I/P (input) connector block. Beware: there's a stray 0V connector in the middle, and a 5V connector at one end. SK8 is the 0V (ground) connector block. J1-J6 connect power and ground lines from the 37-way D connector to the VCC/GND connectors that provide power for the board itself. J7-J30 select high or low voltage ranges for each of the 24 inputs. J31-J54 select optoisolated or logic mode for each of the inputs. J55-J75 short the ground lines together. They are in three blocks of 7, which connect the ground lines of the three blocks of 8 connectors together.


The optoisolators do not work if you reverse +28V and 0V.


Input voltage ranges


In the 'high-voltage' range, 10-30V is considered 'on' or 'high', and anything less is considered 'off' or 'low'. If you want to use 5V inputs instead (where the range 4-12V is considered 'high'), connect the jumpers.


Med Associates inputs


Activating a device shorts its data lead to ground.


So the Amplicon board needs to be set to high-voltage, optoisolated mode. Then all the +28V lines need to be connected to +28V (it's easy to do this by inserting paperclips into the SK7 I/P connectors!); then the ground (SK7, 0V) connectors need to be disconnected from each other by removing J55-75; the data leads can then be wired to the ground connections (SK7). Thus when the device shorts its data lead to ground, the circuit is completed and the optoisolator LED illuminates.


I can't think of an alternative, but it may be worth asking Amplicon if they can redesign the card so shorting the I/P lines together is possible.


Output specifications


The output lines can operate in several modes. (1) "TTL" mode provides TTL voltages (approx. 0V low, +5V high) for low-power devices, such as transistors. If you need to switch high-power devices electronically, you can use these lines to drive the transistor; this is what happens in the Cenes output panels. (2) "Source driver" mode does something slightly mysterious and will be ignored. (3) "High level logic output" mode provides +0.7V (off) or +23V (on) and will drive devices up to 100 mA directly. (4) "Isolated relay contact output" mode switches a relay on the circuit board. When the output is switched on, the relay contact is closed. (There is a second relay contact that behaves oppositely.) This can obviously switch high-power devices that use their own power supply, and is the easy way to switch devices that need more than 100 mA.


Outputs on the EX213 panel


The alternative to relays is logic output. For blocks B and C, this is always high-voltage (0 off, 24V on). For block A only, you can choose high-voltage or TTL voltage (0 off, 5V on) using SK2. The text assumes you are using relays.