Mesa Electronics 7i85 5-channel RS-422 + 4-channel Encoder Daughter Card
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Overview
Mesa 25-pin daughterboard that features 5x RS-422 transceivers (transmit/receive pairs and 5V power) for SmartSerial expansion, as well as 4x RS-422/TTL receivers for encoders.
There also exists a 7i85S that has two transmit channels per connector rather than TX/RX channels, making it suitable for step/direction output in addition to encoder feedback.
Wiring
SmartSerials
| TB Pin | RJ45 Color | Function | Direction | Notes |
|---|---|---|---|---|
| 1 | blue | GND | 7i85 → SS | |
| 2 | blue-stripe | GND | 7i85 → SS | |
| 3 | green | RX+ | 7i85 ← SS | idle = low |
| 4 | green-stripe | RX- | 7i85 ← SS | idle = high |
| 5 | orange | TX+ | 7i85 → SS | idle = low |
| 6 | orange-stripe | TX- | 7i85 → SS | idle = high |
| 7 | brown-stripe | +5V | 7i85 → SS | |
| 8 | brown | +5V | 7i85 → SS |
Encoders
| TB Pin | Function | Direction | RS-422 Mode | TTL Mode |
|---|---|---|---|---|
| 1 | A+ | 7i85 ← Encoder | active high (compared to A-) | TTL input w/ pull-up |
| 2 | A- | 7i85 ← Encoder | active low (compared to A+) | shorted to A+ via 150Ω resistor |
| 3 | GND | 7i85 ↔ Encoder | ||
| 4 | B+ | 7i85 ← Encoder | active high (compared to B-) | TTL input w/ pull-up |
| 5 | B- | 7i85 ← Encoder | active low (compared to B+) | shorted to B+ via 150Ω resistor |
| 6 | +5V | 7i85 → Encoder | ||
| 7 | Z+ | 7i85 ← Encoder | active high (compared to Z-) | TTL input w/ pull-up |
| 8 | Z- | 7i85 ← Encoder | active low (compared to Z+) | shorted to Z+ via 150Ω resistor |
Bill of Materials
| Name | Marking | Part |
|---|---|---|
| P1 | (W) 3.5 [2-pos 3.5mm pluggable header] | |
| P1* | (W) 3.5 [2-pos 3.5mm pluggable terminal block] | Phoenix Contact 1863152 (similar) |
| J1 | AMP2039 A 5747846-4 | TE 5747846-4 |
| TB1,TB2,TB3 | (W) 3.5 [24-pos 3.5mm pluggable header] | |
| TB1* (3x),TB2* (3x),TB3* (3x) | (W) 3.5 [8-pos 3.5mm pluggable terminal block] | Phoenix Contact 1863217 (similar) |
| U1,U4 | [Intersil logo] ISL32173 EFBZ W1829AAZT | Renesas ISL32173EFBZ |
| U2,U6,U9,U10 | [Texas Instruments logo] 0AA4EHK G4 26LS32AC | Texas Instruments AM26LS32ACDR |
| U3 | [Intersil logo] 8491EIBZ K036AFB | Renesas ISL8491EIBZ-T |
| U5 | LVC245A 1500001 YnD913F | Nexperia 74LVC245APW,112 |
| U7 | [NP] | |
| U8 | [onsemi logo] ACT04G PUFM42 | onsemi 74ACT04SC |
| U11 | MV342I 07M AP9J G4 | Texas Instruments LMV342ID |
| U12 | 78M33C TI 05T S83N | Texas Instruments UA78M33CKVURG3 |
Online Resources
7I85 5 Channel RS-422 + 4 Channel Encoder Interface Manual
7I85 4 Channel encoder 5 channel Serial RS-422 interface | Mesa Web Store