Module Configuration Blocks

Module Configuration Blocks#

Analog and temperature modules take a configuration block over the backplane. Both libraries send the factory default at sign-on, so a module reads correctly without one. Send a block only to override that default.

Module	Block length
SLM-AI-8-V, SLM-AI-8-mA	2 bytes
SLM-THM-4	20 bytes
All other modules	None

Every field is a big-endian 16-bit word. A block sent to a module that takes none is ignored.

Channel enable#

Channels are enabled contiguously from CH1, which cannot be disabled. The word is 0x4000 + (n - 1), where n is the number of channels enabled.

Value	Channels
`0x4000`	CH1
`0x4001`	CH1 - CH2
`0x4003`	CH1 - CH4
`0x4007`	CH1 - CH8

SLM-AI-8-V and SLM-AI-8-mA#

Bytes	Field
0-1	Channel enable

Default: 0x40 0x07, all eight channels.

module.configure_module((0x40, 0x03))   # CH1 - CH4 only

SLM-THM-4#

Bytes	Field
0-1	Channel enable, `0x4000` - `0x4003`
2-3	Burnout detection and units
4-5	CH1 range, `0x2100 + code`
6-7	CH2 range, `0x2200 + code`
8-9	CH3 range, `0x2300 + code`
10-11	CH4 range, `0x2400 + code`
12-19	Reserved, write zero

Burnout detection and units:

Value	Meaning
`0x6001`	Low burnout, degrees C
`0x6003`	High burnout, degrees C
`0x6005`	Low burnout, degrees F
`0x6007`	High burnout, degrees F

Range codes, occupying the low nibble of each channel word:

Code	Range	Code	Range
`0x0`	Type J	`0x8`	Type C
`0x1`	Type K	`0x9`	0 - 39 mV
`0x2`	Type E	`0xA`	±39 mV
`0x3`	Type R	`0xB`	±78 mV
`0x4`	Type S	`0xC`	0 - 156 mV
`0x5`	Type T	`0xD`	±156 mV
`0x6`	Type B	`0xE`	0 - 1.25 V
`0x7`	Type N

Default: CH1 - CH4 enabled, low burnout, degrees Fahrenheit, Type J on every channel.

module.configure_module((
    0x40, 0x03,   # CH1 - CH4
    0x60, 0x01,   # low burnout, degrees C
    0x21, 0x01,   # CH1 Type K
    0x22, 0x00,   # CH2 Type J
    0x23, 0x00,   # CH3 Type J
    0x24, 0x00,   # CH4 Type J
    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
))

Important

The factory default is degrees Fahrenheit and Type J on every channel. A Type K sensor read as Type J is linearised with the wrong curve: the error is small near ambient and grows with temperature.