Signal Connections

The peripheral boards installed in the Maestro workstation are connected to various equipment in the laboratory rig. Analog input and output signal lines are exposed on a rack-mounted "breakout panel", while digital IO lines feed into a backplane rack housing various plug-in modules controlled by the 16 outputs of the DIO event timer board. Point-to-point Ethernet connections join Maestro to the RMVideo and EyeLink 1000+ host PCs, and the XYScope controller is connected to an external video output board via a high-density ribbon cable. The analog and digital IO interfaces, the digital plug-in modules, and the video output board are all custom-designed for use with Maestro.

This section details the signal connections from the PC hardware to the external rack interfaces and provides some general information on the design of those interfaces. A complete electrical specification is beyond the scope of this online manual. In the future, however, we hope to provide complete circuit diagrams for the analog IO and digital IO panels, as well as the digital plug-in modules -- as an aid to those who would like to use Maestro but need to construct a new experiment rig.

The diagram above shows the important signal connections from hardware in the Maestro workstation to external equipment in the laboratory rig. Note that connections are shown for Maestro's recommended hardware configuration: (i) a PCIe-6363 multi-function IO board providing AI, AO, and DIO timer functions; (ii) an RTX-supported network adapter for the Ethernet link to RMVideo; (iii) a Windows-compatible network card for the Ethernet connection to the EyeLink 1000+ eye tracker (if used); and (iv) a Detroit C6x DSP card driving the XYScope video-out electronics. The following sections define the six lettered signal pathways in the diagram.

Ethernet connections to RMVideo and the EyeLink tracker (C, F)

Maestro communicates with RMVideo over a private, point-to-point Ethernet connection. There is no intervening hub; you connect each network interface controller (NIC) directly to the other with an RJ-45 Ethernet cable. In the past, we had to use a crossover cable to ensure that the transmit pins of one NIC were connected to the receive pins of the other, and vice versa. Nowadays, modern NICs like the recommended Intel Gigabit CT Desktop Adapter can automatically detect the cable type and configure the connection accordingly. As long as one of the two NICs have this auto-MDIX feature, you can connect them with the more common straight-through or patch cable. If you're not sure that at least one of the NICs supports auto-MDIX, then stick with the crossover cable.

If you intend to use the EyeLink 1000+ eye tracker system, you will need a second NIC in the Maestro PC for that point-to-point connection. The EyeLink NIC remains under Windows control, whereas the RMVideo NIC is under RTX control.

Typically the Maestro PC will also be connected to a local area network through yet another network adapter. Be sure to label all the network ports in use on the outside of the computer so that you know which is which. If you accidentally swap the connections, then you won't have network access and Maestro won't be able to talk to RMVideo or the EyeLink tracker!

XYScope-related connections (D, E) [not available in Maestro 4]

The XYScope video output box (sometimes called the "dotter board") houses the electronics which ultimately drive the X-deflection, Y-deflection, and trigger inputs on the large vector analog oscilloscope on which XYScope targets are displayed. The XYScope controller, implemented on the Detroit C6x DSP card from Spectrum Signal Processing, is responsible for computing dot positions for all targets animated and sending commands to draw every dot. A single "dot draw cycle" involves sending the X and Y coordinates of the dot's position to the video output box. Upon receipt, the video circuit updates the voltages on its X and Y outputs to move the scope's electron beam to the desired position, waits for a short time to allow the beam to settle at the new position, and then raises its trigger output briefly to turn on the beam and "paint" the dot. The controller writes the dot delay and duration parameters to registers in the video output box prior to starting a target animation sequence.

The Detroit C6x is connected to the video output box by a high-density 68-pin ribbon cable conforming to Spectrum's DSP-LINK3 specification. Because data transmission rates are high in order to draw a large number of dots at refresh rates as high as 2 ms, the ribbon cable can only be about 6-12 inches long. Thus, we have to position the video box very close to the Maestro PC. Also, since the Detroit's DSP-LINK3 connector is located on an interior edge of the board, we have to cut a hole in the PC casing and feed the ribbon cable through it to the video box.

Standard coaxial cables are used to connect the BNC outputs of the video box to the relevant inputs on the vector oscilloscope. Both differential and single-ended outputs are available for the X- and Y-deflection signals. Since proper impedance matching is required to maintain signal fidelity, each coaxial cable is generally back-terminated with a series 50-ohm resistor, matching the termination at the monitor end of the cable. This will halve the signal gain, however, which will reduce the maximum beam deflection possible. You will have to make adjustments with the scope's gain controls to get a maximum deflection that uses most of the screen real estate without going beyond its edges.

Analog and digital IO signals (A, B)

In Maestro's recommended hardware configuration (as of version 3.0), all relevant analog and digital IO signals feed into the National Instruments' PCIe-6363 multi-function data acquisition card. This board has two high-density 68-pin back panel connectors. We recommend using two SHC68-68-EPM cables (also from NI) to carry signals on the PCIe-6363 to the rack-mounted interface/breakout panels.

The introduction of the PCIe-6363 required the addition of a "signal mapper" circuit in the equipment rack. This simple circuit maps the relevant signal lines on the PCIe-6363's two 68-pin connectors to the existing 50-pin ribbon-style analog input connector of the Maestro 2.x-era analog IO interface, and the two 40-pin ribbon connectors for the current digital IO interface. The "signal mapper" circuit has allowed the lab to bring Maestro 3.0 online quickly, without having to redesign these existing AIO and DIO interfaces. [Note that the 50-pin analog output connector of the analog IO interface is no longer used, because Maestro 3.0 only makes use of two analog output (since the fiber optic targets have been deprecated), both of which are available on the 50-pin analog input connector.]

The relevant analog signals are accessible from BNC or banana-plug connectors on the front panel of the AIO interface. Analog inputs and outputs are buffered to protect the PCIe-6363 against electrical surges in the signal conditioning modules, and panel-accessible pots permit fine-tuning the DC offset and gain of the analog outputs. (The DC offset for the analog output driving the Chair servo must be adjusted from time to time to minimize position drift.)

The rack-mounted DIO backplane interface accepts the two 40-pin flat ribbon cables from the signal mapper, one carrying digital inputs and one carrying outputs. The connector pinouts remain compatible with the original DIO event timer board from Lisberger Technologies, so no changes had to be made in the interface to accommodate the PCIe-6363. Up to eight plug-in modules can be inserted into the backplane. A single "TTL input" module provides direct access to the 16 digital inputs; users route marker pulses and other external TTL signals to selected inputs on this module so that they can be timestamped by Maestro. The other modules are controlled by commands on a 16-bit digital output port and handle important functions such as: variable-length reward pulse delivery, the Plexon interface, marker pulse delivery, and the pulse stimulus generator.

The accompanying spreadsheet (above) shows the pinouts for the PCIe-6363's connectors and how the signals are employed in Maestro. In that spreadsheet, the 40-pin digital input connector is labelled "DIO J2", while the 40-pin digital output connector is labelled "DIO J3". The complete pinout for these two connectors is covered in the next section.

Signal connections to legacy hardware [not available in Maestro 4]

While users are strongly encouraged to adopt the recommended hardware configuration, Maestro 3 still supports some legacy hardware used by Maestro 2.x. That hardware includes separate boards for analog input, analog output, and the digital IO event timer. These boards were used with the current version of the DIO backplane interface and an older version of the analog IO interface. To guide those who need to use legacy hardware with Maestro 3, and as a reference for those still using Maestro 2, the spreadsheet below lists the connector pinouts for the older devices.

Digital IO. The spreadsheet lists the digital IO signals relevant to Maestro's DIO event timer function and where they can be found on each of the two legacy devices on which that function was implemented. The original DIO timer -- the SGL Timer from Lisberger Technologies -- is connected to the DIO backplane interface via two 40-pin flat ribbon cables, one for the inputs ("J2") and one for the outputs ("J3"). The current DIO backplane rack was designed in accordance with the SGL Timer's pinout. You will note that, to reduce crosstalk and noise, the individual digital input and output lines on each ribbon cable are alternated with lines connected to digital ground. The M62 Timer uses a DSP to emulate the functionality that is implemented in hardware on the SGL Timer. The M62 board from Innovative Integration has 32 general-purpose digital I/O channels accessible via connector JP14, and the firmware which implements the timestamping function programs the first 16 as inputs and the second 16 as outputs. Furthermore, it uses the OUT line of the on-chip timer 0 to implement the "Data Ready" pulse, available on connector JP31. The easiest way to convert an existing laboratory setup from the SGL Timer to the M62 Emulated Timer is to build an adapter which maps the M62's JP14 and JP31 connectors to the pin layout of the SGL Timer connectors. Doing so avoids possibly more complex and expensive changes to the external rig. The UCSF Dept of Physiology's electronics shop designed and built just such an adapter for the Lisberger lab. This adapter mounts directly onto the M62's JP14 and JP31 connectors, which are located near the middle of the board. On the opposite face of the adapter are the two SGL Timer-compatible 40-pin ribbon connectors for digital input and output. Two ribbon cables are routed out the back of the host computer to the digital I/O interface patch panel in the laboratory rig. For more information on this adapter, contact the lab.

Analog Output. Maestro 2.x used analog outputs to control the trajectories of the animal Chair and the translucent screen targets Fiber1 and Fiber2. As of Maestro 3, the latter two targets are no longer supported, and the only required analog output is the one that drives the Chair servo. There are two legacy AO board still supported in Maestro 3: the AT-AO-10 from National Instruments and the PD2-AO-8 from United Electronic Industries. The AT-AO-10 outputs have 12-bit resolution (+/-10V bipolar, LSB voltage increment = 4.883mV). To achieve the required resolution to control the mirror galvanometers governing the positions of Fiber1 and Fiber2, two AO channels (a "coarse" position signal and a "fine" position signal) were dedicated to each motion axis (horizontal and vertical). An external summing circuit formed a weighted sum (coarse + 10 x fine) of these two outputs to generate the position control signal for each galvo. The external summers are unnecessary when the PD2-AO-8 is used because its analog outputs have 16-bit resolution (LSB voltage increment = 305µV) -- although this was never tested in the field. The spreadsheet includes the relevant dedicated AO signals used by Maestro for each supported device. For complete pinouts, consult the appropriate user manual. Note that the AT-AO-10 has a 50-pin flat ribbon cable that was compatible with an older version of our analog IO interface, while the PD2-AO-8 has a 96-pin connector. Again, the easiest way to convert an existing laboratory setup from the AT-AO-10 to the newer PD2-AO-8 is to design an adapter which maps the relevant signals on the PD2-AO-8's 96-pin connector to the layout of the 50-pin I/O connector on the AT-AO-10. The Lisberger lab has designed a "mapping" adapter for use with the PD2-AO-8; contact the lab if interested.

Analog Input. Maestro 2.x used the PCI-6070E (formerly, PCI-MIO-16E1) multi-function data acquisition board as its analog input device. This card has a 68-pin female high-density I/O connector at the back end. Our laboratory used the National Instrument's 68M-50F MIO cable adapter (part # 184670-01) and a 50-pin ribbon cable to connect the PCI-6070E to the original version of the analog IO rack interface. [NOTE: It has been reported that you can get a PCI-6070E with a male 68-pin I/O connector instead of a female one. In this case, you will need the 68F-50M MIO cable adapter (part# 183139-01), NOT to be confused with the 68F-50M DIO adapter (part# 183139-02). Thanks for that, National Instruments!]

The spreadsheet lists only those signals required by Maestro, with pin numbers matching the 50-pin I/O connector pinout of the 6070E. Consult NI's E-Series User Manual for a complete description of the 68- and 50-pin connector pinouts. Most of the analog input channels are dedicated to recording specific behavioral or neuronal response signals, as indicated. The Fiber1/2 target position feedback signals HTPOS, VTPOS, HTPOS2, and VTPOS2 are available in Maestro 2 but not in Maestro 3, which dropped support for those targets. If an AI channel is "unassigned", then it may be used to record any arbitrary signal at the researcher's discretion. Note that Maestro always configures the PCI-6070E in non-referenced single-ended (NRSE) mode. Thus, the analog IO interface must ensure that the ground returns for all 16 channels are connected to the AISENSE pin rather than AIGND. AIGND itself is usually connected to rack ground. See the E-Series User manual for a detailed discussion of the NRSE, referenced single-ended (RSE), and differential (DIFF) modes of operation.

The TTL output DIO7 on the PCI-6070E is set high while Maestro 2.x is running. The signal was used in some rigs to automatically gate power to the light sources for optic-bench targets Fiber1/2 and REDLED1/2 -- so the researcher would not have to power them on/off manually. It is not available in Maestro 3.