Low-Level Tools

These tools bypass the higher-level instrument abstractions for direct interaction with the AR488 bridge and GPIB bus. Use them for debugging, diagnostics, non-standard instruments, and AR488 commands not covered by other tools.

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raw_command

Send a raw ++ command directly to the AR488 bridge. The command is passed through without interpretation. Use this for AR488-specific commands not exposed as dedicated tools.

Parameters

Name	Type	Required	Description
bridge_name	string	Yes	Name of the bridge
command	string	Yes	Full ++ command string (e.g., ++ver, ++addr 5, ++macro 0)

Example

# Read firmware version
result = await client.call_tool("raw_command", {
    "bridge_name": "bench-a",
    "command": "++ver"
})

# Show current GPIB address
result = await client.call_tool("raw_command", {
    "bridge_name": "bench-a",
    "command": "++addr"
})

# Save configuration to NVS flash
result = await client.call_tool("raw_command", {
    "bridge_name": "bench-a",
    "command": "++savecfg"
})

# Read bridge identity name
result = await client.call_tool("raw_command", {
    "bridge_name": "bench-a",
    "command": "++id name"
})

# List stored macros
result = await client.call_tool("raw_command", {
    "bridge_name": "bench-a",
    "command": "++macro"
})

Returns

The bridge response as a string, or (no response) for commands that produce no output:

AR488 GPIB controller 0.51.29

Note

Commands that do not produce output (e.g., ++savecfg, ++default) will return (no response) after a 1-second read timeout. This is expected behavior, not an error.

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raw_scpi

Send raw data on the GPIB bus to a specific address. Lower level than instrument_query / instrument_write — sends data directly without any SCPI interpretation. Useful for instruments with non-standard command sets or binary data transfers.

Parameters

Name	Type	Required	Description
bridge_name	string	Yes	Name of the bridge
address	integer	Yes	GPIB address to send to (0—30)
data	string	Yes	Raw data string to send on the bus
read_after	boolean	No	If true, perform ++read eoi after sending (default: false)

Example

# Send a proprietary command to an older HP instrument
result = await client.call_tool("raw_scpi", {
    "bridge_name": "bench-a",
    "address": 3,
    "data": "F1R3T4",
    "read_after": True
})

# Send data without reading a response
result = await client.call_tool("raw_scpi", {
    "bridge_name": "bench-a",
    "address": 3,
    "data": "F2R4T3",
    "read_after": False
})

Returns

With read_after=true, returns the instrument’s response:

+1.23456E+01

With read_after=false:

Sent to address 3: F2R4T3

---

bus_diagnostic

Run bus diagnostics via ++xdiag. Writes a byte directly to the data or control bus lines and holds it for 10 seconds. Intended for hardware debugging — verifying signal integrity, checking cable continuity, and testing transceiver operation with a multimeter or logic analyzer.

10-second bus hold

This tool holds the bus lines at the specified value for 10 seconds. During this time, no other bus communication is possible. All instruments on the bus may see unexpected signal states. Do not use during active measurements or when other controllers share the bus.

Parameters

Name	Type	Required	Description
bridge_name	string	Yes	Name of the bridge
mode	integer	Yes	0 = data bus (DIO1—DIO8), 1 = control bus (IFC, ATN, SRQ, etc.)
value	integer	Yes	Byte value to write (0—255). Individual bits map to individual lines

Example

# Set all data lines high (DIO1-DIO8 = 0xFF)
result = await client.call_tool("bus_diagnostic", {
    "bridge_name": "bench-a",
    "mode": 0,
    "value": 255
})

# Set only DIO1 high (bit 0)
result = await client.call_tool("bus_diagnostic", {
    "bridge_name": "bench-a",
    "mode": 0,
    "value": 1
})

# Test control bus — set ATN high
result = await client.call_tool("bus_diagnostic", {
    "bridge_name": "bench-a",
    "mode": 1,
    "value": 128
})

Returns

Diagnostic: writing 0xFF to data bus on bench-a for 10 seconds

Data bus bit mapping (mode 0):

Bit	Value	Line
0	1	DIO1
1	2	DIO2
2	4	DIO3
3	8	DIO4
4	16	DIO5
5	32	DIO6
6	64	DIO7
7	128	DIO8

---

parallel_poll

Conduct a parallel poll on the GPIB bus. Simultaneously reads one status bit from each configured device, returning the combined response byte. Each bit corresponds to a device that has been configured for parallel poll response via the PPE (Parallel Poll Enable) command.

Parameters

Name	Type	Required	Description
bridge_name	string	Yes	Name of the bridge

Example

result = await client.call_tool("parallel_poll", {
    "bridge_name": "bench-a"
})

Returns

Parallel poll result: 0x05 (decimal 5)
  Binary: 00000101
  DIO lines: DIO1=1 DIO2=0 DIO3=1 DIO4=0 DIO5=0 DIO6=0 DIO7=0 DIO8=0

Note

Devices must be configured for parallel poll response before this returns meaningful data. Most instruments are configured via the PPC (Parallel Poll Configure) bus command, which assigns each device to a specific DIO line and polarity. Without configuration, all bits will read as 0.